update of lbwd’s seawaterupdate of lbwd’s seawater ... of lbwd’s seawaterupdate of lbwd’s...

American Water Works AssociationAmerican Water Works Association2009 Annual Conference and Exposition

Update of LBWD’s SeawaterUpdate of LBWD’s Seawater Desalination ResearchDesalination Research

Tai J. Tseng, Robert C. Cheng, and Kevin L. WattierLong Beach Water DepartmentLong Beach Water Department

June 16, 2009

Presentation Outline

Long Beach OverviewLong Beach Overview

Research Fouling Control

Post Treatment

ConclusionConclusion

2009 ACE LBWD 2




Post Treatment


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Long Beach Water Departmentg pCalifornia’s 5th most populous city (~500,000 residents)70,000 AF of drinking water per year8,000 AF of reclaimed water per yearOperate largest GW treatment plant in US900+ miles of drinking water lines750+ miles of sewer lines

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LBWD’s Resource Mix

20092009 2015201520092009 20152015

Conservation15% Imports

Conservation14%

Reclaimed

Reclaimed12%

30%Imports42%

6%

Desal10%

Groundwater33%

Groundwater38%

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LBWD’s Desalination ProgramgA $20 M, 10A $20 M, 10--year investment year investment Leverage various partnerships for technical input and other supportLeverage various partnerships for technical input and other supportLeverage various partnerships for technical input and other supportLeverage various partnerships for technical input and other supportFederal / State / Local FundingFederal / State / Local Funding

Post treatment / DistributionPretreatment NF2 or RO

•Under Ocean Floor Intake and Discharge

•Prototype•UV/ClO2 for disinfection and

•DBP Control•Stability of Disinfectant Residual•Mitigation of WQ impacts due

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Discharge biofouling control •Mitigation of WQ impacts due to integration of new source




Post Treatment


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Fouling ControlgLooking for ways to help meet primary disinfection while

Energy R

minimizing O&M costs through controlling fouling.

Recovery

UV2nd Pass NF

Energy Recovery

1st Pass NFCartridge

Filter

Disinfectant

Pre-Treatment

Recovery

Cartridge Filter

Disinfectant

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2nd Pass NF1st Pass NFClO2

Fouling ControlInitial Bench Testing using SEPA Cell

g

• System operated in recirculation mode.

• ClO2 generated using Cl2 gas &using Cl2 gas & NaClO2.

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Fouling ControlRapid deterioration in salt rejection after ClO2 exposure

g

• Salt rejection 5.0 100%ClO2

decreased by ~ 50% in 4 days suggest the ClO2 3 0

3.54.04.5

ClO

2 (m

g/L)

60%70%80%90%

n

Rejection

suggest the ClO2was rapidly destroying the PA 1.5

2.02.53.0

entra

tion

of C

30%40%50%60%

Rej

ectio

membrane.

0.00.51.0

11/16 11/17 11/18 11/19 11/20 11/21

Con

ce

0%10%20%

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11/16 11/17 11/18 11/19 11/20 11/21

Fouling Controlg

Many ways to generate ClO2.Many ways to generate ClO2.2NaClO2 + Cl2(g) 2ClO2(g) + 2NaCl.2NaClO2 + HOCl 2ClO2(g) + NaCl + NaOH.2NaClO2 HOCl 2ClO2(g) NaCl NaOH.5NaClO2 + 4HCl 4ClO2(g) + 5NaCl + 2H2O.Electrolytic generation.

Depending on the generation method, free Cl2 may be present. The key is to 2 y p ygenerate ClO2 without generating free Cl2.

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2

Fouling ControlRevised Bench SEPA Cell testing

g

• Operated in once-thru mode.• Acid / chlorite method (“free Cl2” free).

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Fouling ControlSEPA Cell testing using ClO2 generated via acid

g

generation method over 14 days• Salt rejection was

90%

100%

0 9

1.0

stable thru the 14 day test period.

• Provided 60%

70%

80%

90%

(%)

0 6

0.7

0.8

0.9

l (m

g/L)Rejection

ClO2Provided reasonable assurance to 30%

40%

50%

60%R

ejec

tion

0.3

0.4

0.5

0.6

lO2 R

esid

uaid l

proceed to testing on full-scale

0%

10%

20%

7/1 7/6 7/11 7/16 7/210.0

0.1

0.2 Cl

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7/1 7/6 7/11 7/16 7/21

Fouling ControlgPrototype testing of ClO2 began in April

1.6Feed

• Target dose is 0.5

1.0

1.2

1.4

l (m

g/L)

FeedConcentratePermeate

mg/L.• Interestingly, ClO2

was 100% rejected

0 4

0.6

0.8

O2 R

esid

ualwas 100% rejected

by membranes. • This can impact

0.0

0.2

0.4

3/28 4/17 5/7 5/27 6/16

Cl

how we use ClO2 to assist in meeting CT

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3/28 4/17 5/7 5/27 6/16CT.

Fouling ControlPerformance with ClO2 over the last 42 days

g

• Average ClO2 Stage 1 Cond. Stage 2 Cond. average exposure

exposure ~ 0.6 mg/L.

• Total exposure ~ 10

12

14

mS)

4.0

5.0

pm)

Total exposure 580 ppm-hours.

• Maintaining salt 4

6

8

ondu

ctivity

(m

2.0

3.0

O2 R

esidual (p

rejection.0

2

4

3/18 4/7 4/27 5/17 6/6

Co

0.0

1.0 ClO

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3/18 4/7 4/27 5/17 6/6

Fouling ControlCF DP with and without ClO2

g

18

20

With C lO2 Without C lO2

12

14

16

sure (PSI)

Generator malfunction

6

8

10

eren

tial P

res

2

4

6

Diffe

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0

4/1 4/6 4/11 4/16 4/21

Fouling ControlCloser examination of cartridge filter ΔP

g

Cartridge

Train 1

Filter

Initially No ClO2Started ClO2

Pre-TreatmentCartridge

Filter

Stopped ClO2

Train 2

Initially With ClO

Train 2

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Initially With ClO2Stopped ClO2Started ClO2

Fouling ControlShort experiments to evaluate ClO2

g

16 180

T1 DP T2 DP T1 Flow T2 Flow

10

12

14

(psi

)

120

140

160

)

Stopped ClO2 Injection

6

8

10

ta P

ress

ure

60

80

100

120

Flow

(GP

M)

Started ClO2 Injection

Stopped ClO2 Injection

0

2

4Del

0

20

40

60

Started ClO2 Injection

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0

04/2

4

04/2

5

04/2

6

04/2

7

04/2

8

04/2

9

04/3

0

0




Post Treatment


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Post TreatmentGoal: Test impact of blending desal permeate p g pon corrosion Pipe loop test matrixPipe loop test matrix

3 waters: DSW (control), NF2 blend and NF2

blend (replicate but with different biofoulingblend (replicate but with different biofouling control strategies)5 pipe materials: CML-DI (new), CML-steel (new-p p ( ), (simulate asbestos cement), UCI (harvested), copper service pipe (new), and copper with lead

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solder.

Post Treatment

Pipes both harvestedPipes both harvestedPipes, both harvested Pipes, both harvested and new, were and new, were conditioned withconditioned withconditioned with conditioned with distribution system distribution system water to condition thewater to condition thewater to condition the water to condition the pipes prior to pipes prior to installationinstallationinstallation.installation.

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Post Treatment

Finished Pipe LoopFinished Pipe LoopFinished Pipe Loop.Finished Pipe Loop.Pipe loops are enclosed in Pipe loops are enclosed in temperature controlledtemperature controlledtemperature controlled temperature controlled environment.environment.3 Trains:3 Trains:

Each Train has 4 pipe Each Train has 4 pipe materials operated in materials operated in parallel.parallel.parallel.parallel.

Copper with lead solder is Copper with lead solder is outside.outside.

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Post TreatmentPipe loop 1 Pipe loops 2 & 3Pipe loop 1 Pipe loops 2 & 3

6 months Preconditioning DSW DSW

Phase 1‐ 6 months DSW NF2:DSW ratio 50:50

Phase 2 4 months DSW NF2:DSW ratio 75:25

6 months Preconditioning DSW DSW


Phase 2 4 months DSW NF2:DSW ratio 75:25Phase 2‐ 4 months DSW NF2:DSW ratio 75:25

Phase 3‐ 2 months DSW TBD


Phase 3‐ 2 months DSW TBD

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar AprOffsite ConditioningOnsite Conditioning

2009 2010

Onsite ConditioningPhase 1 TestingPhase 2 TestingPhase 3 Testing

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Post Treatment

Chlorine residual hasChlorine residual has2.0

L)

DSW-CastTrain 1-CastTrain 2 Cast Chlorine residual has Chlorine residual has

reached a stable level in reached a stable level in cast iron, ductile iron and cast iron, ductile iron and t l it l i

1.0

1.5

tal c

hlor

ine

(mg/ Train 2-Cast

steel pipessteel pipes

0.0

0.5

2/16/09 3/8/09 3/28/09 4/17/09 5/7/09

Tot

2/16/09 3/8/09 3/28/09 4/17/09 5/7/09

1.5

2.0

(mg/

L)

1.5

2.0

(mg/

L)

0.5

1.0

Tota

l chl

orin

e

DSW-DuctileTrain 1-DuctileT i 2 D til

0.5

1.0

Tota

l chl

orin

e

DSW-SteelTrain 1-SteelTrain 2 Steel

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0.02/11/09 2/26/09 3/13/09 3/28/09 4/12/09 4/27/09 5/12/09

Train 2-Ductile

0.02/16/09 3/8/09 3/28/09 4/17/09 5/7/09 5/27/09

Train 2-Steel

Post Treatment

Iron samples takenIron samples taken

12000

14000DSW-CastTrain 1-CastTrain 2 Cast

Iron samples taken Iron samples taken from Unlined Cast Iron from Unlined Cast Iron Pipe after 6 hours of Pipe after 6 hours of t ti h th tt ti h th t

8000

10000

n (u

g/L)

Train 2-Cast stagnation shows that stagnation shows that iron release gradually iron release gradually decreased during decreased during

2000

4000

6000

Iron

conditioning period conditioning period and is ready for and is ready for blending studyblending study

02/11/09 2/26/09 3/13/09 3/28/09 4/12/09 4/27/09

blending study.blending study.

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Post Treatment

Target WQ ConditionsTarget WQ Conditionsgg

DSWTargetParameter

NF2:DSW

ConditionTarget

ConditionAdjustment Method

pH 7.8 ‐ 8.4 8.0 ‐ 8.2Aerate NF Permeate, adjust pH usine NaOH or H2SO4

Parameter

usine NaOH or H2SO4

Alkalinity 73 ‐ 136 60 ‐ 100Add ~ 40 mg/L Alkalinity to NF Permeate using NaHCO3

Add 2 8 /L Chl i NFChlorine 2.0 2.5

Add ~ 2.8 mg/L Chlorine to NF Permeate

Ammonia 0 5 0 6Add Ammonia to DSW before

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Ammonia 0.5 0.6blending

Post Treatment

Parameters Monday Tuesday Wednesday Thursday FridayParameters Monday Tuesday Wednesday Thursday FridaypH, Conductivity, and ORP X X XTotal and Free Chlorine X X XAlkalinity X X XDO X X XTemperature X X XSulfide XT l d F A i X X XTotal and Free Ammonia X X XMetals X X XAnions and Cations X X XColiform, HPC XColiform, HPC XColor, Turbidity, and TDS XTOC, DOC, and UV254* XHAA9 and TTHM** X

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Iodide, Iodine, IA, and NDMA ** X*Twice a month, **Once a month



Research Pre-Treatment

Post Treatment


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ConclusionsGeneration method for ClO2 is key. 2 y“Free chlorine” free ClO2 have been successfully applied onto PA membranes for y580 ppm-hours without noticeable damage to the membranes. ClO2 is rejected during the desalination process.The application of chlorine dioxide controlled biofouling in cartridge filter system.

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ConclusionsPost treatment testing facility construction is g ycomplete.CI, DI, and Steel preconditioning stability. g yDuring preconditioning, pipes were superchlorinated and may have destabilized scale. However, more recent data suggest the new scale formation is stronger than previous

lscale.Blending studies have began and will proceed for the next 6 months

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for the next 6 months.

AcknowledgementgFunding partners:

US Bureau of ReclamationCa Dept of Water ResourcesLos Angeles Dept of Water and PowerLos Angeles Dept of Water and Power

Dian Tanuwidjaja, UCLA/LBWDDuPont (ClO2 analytical support) ( 2 y )CH2M (ClO2 design & technical support)Yan Zhang, DXV WaterB&V (Post Treatment design & technical support)LBWD WQ Lab Staff

2009 ACE LBWD 31

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