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Algae Removal from Algae Removal from Wastewater Treatment Pond Effluent Wastewater Treatment Pond Effluent by Dissolvedby Dissolved--Air FlotationAir Flotation

Dr. Yakup NurdoganDr. Yakup NurdoganCDM, 11811 N.E. 1CDM, 11811 N.E. 1stst StreetStreetBellevue, WA 98005Bellevue, WA 98005425425--519519--83758375 nurdogany@cdm.comnurdogany@cdm.com

September 14, 2009September 14, 2009

Presentation OutlinePresentation Outline

�� Dr. William J. Oswald Dr. William J. Oswald –– HRP pioneerHRP pioneer

�� Experimental HRP systemExperimental HRP system

�� Selection of colonial algae species in HRPSelection of colonial algae species in HRP

�� Microscopic photos of colonial algae Microscopic photos of colonial algae MicractinumMicractinum and and ScenedesmusScenedesmus

�� Advanced dissolved air flotation systemAdvanced dissolved air flotation system

�� DAF clarification resultsDAF clarification results

�� DAF vs. sedimentation clarifierDAF vs. sedimentation clarifier

�� HRP vs. Activated SludgeHRP vs. Activated Sludge

�� ConclusionsConclusions

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Dr. William J. OswaldDr. William J. OswaldPioneer of HRP TechnologyPioneer of HRP Technology

Dr. William J. Oswald’s Handwriting ! Dr. William J. Oswald’s Handwriting !

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Experimental HRP SystemExperimental HRP System

PaddlePaddle--Wheel Mixing of HRPWheel Mixing of HRP

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Plan View of Two 1,000 mPlan View of Two 1,000 m22 HRP HRP

SettledSewage

TapWater

CaO8

Pond Effluents

East PondEast Pond

West PondWest Pond

PaddlePaddleWheelWheel

23 M

95 M

Symbiotic Relationship Between Symbiotic Relationship Between Microalgae and Bacteria in HRPMicroalgae and Bacteria in HRP

BacteriaBacteria

COCO22NHNH33

OO22

AlgaeAlgae

New CellsNew Cells

OrganicsOrganicsplus Oplus O22

New CellsNew CellsSunlightSunlight

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Algae Abundance in PondsAlgae Abundance in Ponds

Ponds in the USA (Oswald, 1976) Rank Richmond HRPs in This Study, 1982-85

Chlorella 1 Micractinium

Ankistrodesmus 2 Scenedesmus

Scenedesmus 3 Ankistrodesmus

Euglena 4 Chlorella

Chlamydomonas 5 Chlamydomonas

Oscillatoria 6 Euglena

Micractinium 7 Oscillatoria

Factors Affecting the Selection of Algal Factors Affecting the Selection of Algal Genera in HRPGenera in HRP

Parameters Micractinium Scenedesmus Chlorella Motile Algae

Pond Depth, cm 40 - 50 20 - 30 15 – 20 > 50

Hydraulic Detention Time, days 3 – 6 4 – 8 1 – 2 > 10

Organic Loading mg COD/L/day 50 – 100 150 – 300 25 – 75 > 500

Mixing Type P. Wheel P. Wheel Pump None

Linear Mixing Velocity, cm/sec 15 – 25 10 – 15 5 – 10 0

Pond pH 8 – 10 8 – 10 7 – 9 7 – 8

Pond Water Temperature, ºC 10 – 20 10 – 30 15 – 35 5 - 15

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Linear Mixing Velocity in HRP vs. Linear Mixing Velocity in HRP vs. PaddlePaddle--Wheel RPMWheel RPM

4040

3030

2020

1010

00

Linear Mixing Velocity (cm/sec)

Linear Mixing Velocity (cm/sec)

Paddle Wheel Speed (rpm)Paddle Wheel Speed (rpm)

00 22 44 66 88

Paddle Wheel Tip VPaddle Wheel Tip V

VV = 0.53 V= 0.53 V

ChannelChannel

32 cm Depth32 cm Depth39 cm Depth39 cm Depth

MicractiniumMicractinium

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MicractiniumMicractinium

ScenedesmusScenedesmus

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Bioflocculating Bioflocculating ScenedesmusScenedesmus CellsCells

MicractiniumMicractinium and and ScenedesmusScenedesmus

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Autoflocculated Autoflocculated MicractiniumMicractinium

MicractiniumMicractinium Solids in 1Solids in 1--hr Settling hr Settling TestTest

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Pilot DAF UnitPilot DAF Unit

Advanced DAF Advanced DAF -- Rotating Inlet and Rotating Inlet and OutletOutletInlet FlowInlet FlowAt the pressure release valve (1) At the pressure release valve (1) absorbed air is released into the water. absorbed air is released into the water. The water flows in at the exact center, The water flows in at the exact center, through a rotary joint (2) and into through a rotary joint (2) and into the distribution duct (3).the distribution duct (3).

Clarified Water OutletClarified Water OutletThe clarified water, near the bottom, isThe clarified water, near the bottom, isremoved by slotted outlet pipes (5) attached removed by slotted outlet pipes (5) attached to the wall of the moving center part. Clean to the wall of the moving center part. Clean water flows into the center section (6) and water flows into the center section (6) and overflows over the telescopic weir (7).overflows over the telescopic weir (7).

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22 33

55

66

77

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Advanced DAF Advanced DAF -- Outlet and Spiral Float Outlet and Spiral Float ScoopScoop

Single ScoopSingle Scoop

Double ScoopDouble Scoop

Triple ScoopTriple Scoop

An Elevated 33An Elevated 33--ft Diameter DAF Unit ft Diameter DAF Unit for 2,400 gpm Flowfor 2,400 gpm Flow

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A 70A 70--ft Diameter DAF Unit for 11,800 ft Diameter DAF Unit for 11,800 gpm Flowgpm Flow

Klett Unit vs. SS ConcentrationKlett Unit vs. SS Concentration

250250

200200

150150

100100

5050

00

SS Concentration (mg/L)

SS Concentration (mg/L)

Optical Density (Klett Unit)Optical Density (Klett Unit)

00 2020 4040 6060 8080

y = 2.6x y = 2.6x –– 8.8 (R = 0.97)8.8 (R = 0.97)

100100

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Alum CoagulationAlum Coagulation

100100

8080

6060

4040

2020

00

SS Removal Efficiency, (%)

SS Removal Efficiency, (%)

Alum Dose (mg/L)Alum Dose (mg/L)

00 5050 100100 150150 200200

Optimum pH: 6.0 Optimum pH: 6.0 –– 6.56.5

250250 300300 350350

ScenedesmusScenedesmus

MicractiniumMicractinium

Ferric Chloride CoagulationFerric Chloride Coagulation

100100

9090

8080

7070

6060

5050

SS Removal Efficiency, (%)

SS Removal Efficiency, (%)

FeClFeCl33 Dose (mg/L)Dose (mg/L)

00 2525 5050 7575 100100

Optimum pH: 5.0 Optimum pH: 5.0 –– 6.06.0

125125 150150

MicractiniumMicractinium

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Effect of DAF Underflow Rate on Effect of DAF Underflow Rate on Effluent SS ConcentrationEffluent SS Concentration

6060

5050

4040

3030

2020

1010

00

DAF Effluent SS Concentration (mg/L)

DAF Effluent SS Concentration (mg/L)

Underflow Rate (gpm/ftUnderflow Rate (gpm/ft22))

1.51.5 1.71.7 1.91.9 2.12.1 2.32.3 2.52.5 2.72.7

AlumAlumFerric ChlorideFerric ChlorideNalco’s UtrionNalco’s Utrion--81098109

Effect of DAF Underflow Rate on SS Effect of DAF Underflow Rate on SS Removal EfficiencyRemoval Efficiency

100100

9090

8080

7070

DAF SS Removal Efficiency (%)

DAF SS Removal Efficiency (%)

Underflow Rate (gpm/ftUnderflow Rate (gpm/ft22))

1.51.5 1.71.7 1.91.9 2.12.1 2.32.3 2.52.5 2.72.7

AlumAlumFerric ChlorideFerric ChlorideNalco’s UtrionNalco’s Utrion--81098109

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Effect of DAF Recycle Ratio on Effluent Effect of DAF Recycle Ratio on Effluent SS ConcentrationSS Concentration

Recycle RatioRecycle Ratio

6060

4040

2020

000.450.45 0.50.5 0.550.55 0.60.6 0.650.65 0.70.7 0.750.75

AlumAlumFerric ChlorideFerric ChlorideNalco’s UtrionNalco’s Utrion--81098109

DAF Effluent SS Concentration (mg/L)

DAF Effluent SS Concentration (mg/L)

0.80.8

Effect of DAF Recycle Ratio on SS Effect of DAF Recycle Ratio on SS Removal EfficiencyRemoval Efficiency

100100

9090

8080

70700.450.45 0.50.5 0.550.55 0.60.6 0.650.65 0.70.7 0.750.75

AlumAlumFerric ChlorideFerric ChlorideNalco’s UtrionNalco’s Utrion--81098109

DAF Effluent SS Removal Efficiency (%)

DAF Effluent SS Removal Efficiency (%)

0.80.8

Recycle RatioRecycle Ratio

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Advanced DAF vs. Sedimentation Advanced DAF vs. Sedimentation Clarifier Costs for 7.5 MGD flowClarifier Costs for 7.5 MGD flow

*Cost of chemical remains the same for equal clarification

Items Advanced DAF Sedimentation Clarifier

Diameter 44 ft 112 ft

Depth 2 ft 7 ft

Detention Time 3 min 110 min

Sludge Consistency 2 – 3% 0.5 – 1.0 %

Power Consumption:

Feed Pump 44 KW Feed Pump 44 KW

Recycle Pressure Pump 51 KW Scraper 12 KW

DAF Drive 3 KW

Compressor 1 KW

Total: 99 KW 56 KW

Equipment Cost: $512,000 $1,344,000

Operational Cost: 3 c/1000 gal 8 c/1000 gal

HRP vs. Activated SludgeHRP vs. Activated Sludge

Parameters Raw Sewage HRP System

Conventional Activated Sludge System

SecondaryTreatment

Phosphorus Removal

Nitrogen Removal

BOD, mg/L 200 5 – 10 20 – 30 10 – 20 4 – 10

% Removal - 95 – 98 85 – 90 90 – 95 95 - 98

COD, mg/L 400 60 – 80 80 – 120 40 – 60 20 - 40

% Removal - 80 – 85 70 – 80 85 – 90 90 - 95

SS, mg/L 200 20 – 40 20 – 40 20 – 40 20 – 40

% Removal - 80 – 90 80 – 90 80 – 90 80 – 90

PO4-P, mg/L 10 0.1 – 0.5 7.5 – 9.0 0.5 – 1.0 0.1 – 0.5

% Removal - 95 – 99 10 – 25 90 – 95 95 – 99

NH4-N, mg/L 20 2 – 3 16 – 18 15 – 17 0.2 – 0.4

% Removal - 85 – 90 10 – 20 15 – 25 98 - 99

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ConclusionsConclusions�� DAF is an efficient and reliable method for DAF is an efficient and reliable method for

algae harvesting from HRP.algae harvesting from HRP.

�� DAF effluent SS concentrations were 30 DAF effluent SS concentrations were 30 mg/L or better when chemical coagulants mg/L or better when chemical coagulants were used without any polymer. were used without any polymer.

�� The optimum DAF underflow rate: 2.0The optimum DAF underflow rate: 2.0--2.3 2.3 gpm/ftgpm/ft22 to achieve a DAF effluent SS to achieve a DAF effluent SS concentration of 30 mg/L.concentration of 30 mg/L.

�� The optimum recycle ratio: greater than 55The optimum recycle ratio: greater than 55--65% to achieve a DAF effluent SS 65% to achieve a DAF effluent SS concentration of 30 mg/L. concentration of 30 mg/L.

�� Optimum coagulant dosages obtained by jar Optimum coagulant dosages obtained by jar test settling are not optimum for flotation.test settling are not optimum for flotation.

ConclusionsConclusions�� MicractiniumMicractinium is easier to flocculate than is easier to flocculate than ScenedesmusScenedesmus..

�� Optimum coagulant dosages based on the jar Optimum coagulant dosages based on the jar test settling:test settling:�� Nalco’s UtrionNalco’s Utrion--8109: 45 mg/L8109: 45 mg/L

�� Ferric chloride: 80 mg/LFerric chloride: 80 mg/L

�� Alum: 150 mg/L for Alum: 150 mg/L for MicractiniumMicractinium and 250 mg/L and 250 mg/L for for ScenedesmusScenedesmus species.species.

�� DAF float solids concentrations were 2.7DAF float solids concentrations were 2.7--3.4 % 3.4 % by wt without any polymer usage.by wt without any polymer usage.

�� Polymer addition will improve the clarification Polymer addition will improve the clarification by reducing coagulant dosages required and by reducing coagulant dosages required and increase float solids concentrations.increase float solids concentrations.