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Improving Efficiency of DewateringAlternatives to Conventional Dewatering

Technologies

Robert Gillette, PE, BCEESteve Swanback, PE

Rebecca Overacre, PE

2009 PNCWA Webinar Recent Developments In

Biosolids Management Processes

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Outline

1. Screw press technologya. Performance survey resultsb. Pilot testing resultsc. Lifecycle cost evaluation (Class A and Class B)d. Design considerations

2. Rotary fan press technologya. Performance survey resultsb. Pilot testing resultsc. Lifecycle cost evaluation (Class A and Class B)d. Design considerations

3. Overview of R&D Technologies

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Screw Press Technology

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Screw Press Manufacturers

• Huber (inclined)

• FKC (horizontal)

Screw Press General Description

Dewatering by Volume Reduction

Screw Press Expanded View

Screw Press Expanded ViewClass A Option

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Flow Schematic

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Tallahassee, FL, FKC InstallationTallahassee, FL, FKC Installation

FKC Screw Press

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FKC Screw Press

Petaluma, CA, FKC InstallationPetaluma, CA, FKC Installation

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Huber Press

Magna, UT, Huber InstallationMagna, UT, Huber Installation

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Huber Press

Maine, Huber InstallationMaine, Huber Installation

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Performance Survey

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Survey of 22 Full Scale Installations –The Cake Solids Concentration Depends on Type of Sludge

Type of Sludge Screw Press Cake (% solids)FKC 15 – 20

FKC (with steam and lime) 20 – 45Huber 12 – 20FKC 21 – 28

WAS

Huber 22 – 25Raw Huber 18 – 40

PS+WASFKC > 18

Huber 19 – 24Aerobically Digested

Anaerobically Digested

FKC 17 – 25Anaerobically Digested Huber 13 – 16

Raw

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Survey of 22 Full Scale Installations –The Median Cleaning Schedule is Once Per Week

Manual Cleaning Schedule(times per month)

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22Facility Number

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Case Study –St Petersburg, FL

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Pilot Results - Projected Full Performance – St. Petersburg

Manufacturers Recommendations

Screw PressBelt Press CentrifugeClass B Class A

Minimum Cake Solids Concentration (% solids)

18 21 16 33

Maximum Polymer Dosage (lb/DT)

19 25 30 33

Minimum Solids Capture (%)

95 95 90 90

Parameter

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“Relative” Cost Comparison

BFP Centrifuge Screw Press

Capital Cost $ $$$ $$

Building Modifications $ $$ $$

Odor Control $$$ $ $

Power $ $$$ $

Maintenance $$ $$ $

Chemical $$ $$$ $$

Hauling $$ $ $$

Disposal $$ $ $$

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Performance Comparison

Will Vary Depending on Conditions!!!Will Vary Depending on Conditions!!!

BFP Centrifuge Screw Press

% Solids Produced ++ +++ +

Filtrate/Centrate Quality ++ ++ +

Reliability ++ ++ +++

Operator Attention Required + ++ +++

Ease of startup and shutdown ++ + ++

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Design Considerations

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Design Considerations

• Lead time (from Japan or Germany): prepurchase?

• Custom design – varying dimensions until shop drawing

• Performance guarantee and penalty for non-compliance

• Basis of design– Loading & capacity: pilot test– Run time, unattended operation

• Effect of rising steel costs – units all SST

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Design Considerations, Continued

• Need headroom if RST on mezzanine• Monorail/overhead crane• Building considerations – footprint

requirement – or outside• Provision for Class A in future• Cake conveyance options affects layout

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Design Parameters

• Range of Capacity: Up to 8.5 DT/day– At “nominal” speed

• RST output (% Solids): around 4%• Screw Press output (% Solids): 15 – 28%• Polymer consumption: 20 – 40 lb/DT• Detention time: approximately 4 hours• Motor speed: as low as 0.3 rpm• Motor HP – largest unit is 7.5 HP

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Rotary Press Technology

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Rotary Press Manufacturers

Fournier

Prime Solutions

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Rotary Press Schematic

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Process Cutaway

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Design Parameters

• Range of Capacity: 7-250 gpm• Cake % Solids: 12 – 28%• Detention time: N/A• Motor speed: as low as 1-3 rpm• Motor HP: 5-20 HP

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Fournier Rotary Press

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• Size Compared to Other Technologies

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Multiple Channels on Single Drive

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Fournier Rotary Press Pilot Test

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Prime Solutions Rotary Fan Press

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Performance Survey

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Survey Results

Facility EquipmentFacility

Size (mgd)

Solids Type Incoming % TS

Discharge % TS

Raiford, FL Prison WWTP

Rotary fan press 1.1 Extended aeration

1.6-2.5 19-22

Front Royal, VAMunicipal WWTP

Rotary fan press 3.3 Thermophilic Anaerobic Digestion

3.5 25

Fairfield, CAMunicipal WWTP

Rotary fan press 15.5 Conventional Anaerobic Digestion

2 17

Lafayette, TNMunicipal WWTP

Rotary press 0.5 Conventional Anaerobic Digestion

1.0-1.5 25

Portland, MEMunicipal WWTP

Rotary press 19.8 Thickened PS/WAS

3-6 19-25

Hampton, NHMunicipal WWTP

Rotary press 2.5 Septage/PS/WAS

6-8 26-28

Murfreesboro, TNMunicipal WWTP

Rotary press 15 PS/WAS 0.8-1 12-14

Scarborough, MEMunicipal WWTP

Rotary press 1.4 Thickened PS/WAS

3 28

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Rotary Dewatering Features

• Low speed, low vibration, low shear• Uses less energy than centrifuges or BFPs• Modular• Small footprint• Minimal start-up and shutdown time• Minimal moving parts• Odors contained

Questions?

Bob Gillettergillette@carollo.com

916-565-4888

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R&D Technologies

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EKG Technologies

• Electrokinetic Geosynthetics (EKG) Technology– Theory – Electro-osmotic principle

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Uses of EKG Technology

• Ashbrook Product– Anaerobically/Aerobically Digested

Sludge• Fresno• England

– Alternative to conventional dewatering

• Siemen’s Product– Secondary dewatering process– Alternative to sludge drying

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Siemen’s ELODE Technology

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Siemen’s ELODE Technology

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Siemen’s ELODE Technology

Questions?

Bob Gillettergillette@carollo.com

916-565-4888