MTBE treatment.pdf

Aggregate WaterTreatment Costs due to

MTBE ContaminationArturo A. Keller1

Orville C. Sandall2Robert G. Rinker2Linda Fernandez1Marie M. Mitani1

Britta Bierwagen1Michael J. Snodgrass2

1Bren School of EnvironmentalScience and Management

2Dept. of Chemical Engineering

University of California, Santa Barbara

Cost Elements

z Unit water treatment costyReview of applicable technologies

z Extent of current contaminationyLeaking USTs (LUFTs)yContaminated drinking water wellsyPipeline failuresySurface water reservoirs

z Contribution of MTBE to remediation cost

Unit Water Treatment Costz Applicable TechnologiesyAir StrippingyGranular Activated CarbonyBiofiltrationyAdvanced Oxidation ProcessesyHollow Fiber Membranes

z Scenarios:yHigh concentration/low flowrateyLow concentration/high flowrateyTreat to 5 ug/L

Physicochemical DataProperties at 25oC MTBE ETBE TAME TBA Ethanol

Vapor Pressure (atm) 0.330 0.200 0.090 0.054 0.069Aqueous solubility(mg/L)

43,000 to54,300

26,000 20,000 ¥ ¥

Henry’s Law Constant(Mol L Mol-1 L-1)

0.024 to0.123

0.109 0.052 4.3x10-4

to5.9x10-4

2.1x10-4 to2.6x10-4

Octanol-WaterPartitioning Coefficient,Kow (-)

101.2 101.74 No data 100.35 10-0.16 to10-0.31

Boiling Point (oC) 55.2 67 86.3 82.9 78.5Density (g/mL) 0.74 0.73 0.77 0.79 0.79Molecular Weight(g/mole)

88.15 102.18 102.18 74.12 46.07

CAS Number 1634-04-4 637-92-3 994-05-8 75-65-0 64-17-5

Cases Used in Study

Case 1 2 3 4 5 6 7 8 9 10

Concentration (ug/L) 100 100 100 500 1000 5000 100 500 1000 5000Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10

z Scenarios:yLUFT: High concentration/low flowrateyDrinking water well or surface water

reservoir: Low concentration/high flowrateyTreat to 5 ug/L

Air StrippingLow Flow

rateMediumFlow rate

High Flowrate

Very HighFlow rate

Water Flow rate(m3/s)

6.3x10-4

(10 gpm)0.0063

(100 gpm)0.031

(500 gpm)0.063

(1000 gpm)

Tower Diameter 0.36 m(1.2 ft)

1.13 m(3.7 ft)

2.54 m(8.3 ft)

3.6 m(11.8 ft)

Tower Height Packing height + 3 mPacking Material 1" Intalox SaddlesVolumetric Air-Water Ratio

150:1

PlannedOperatingSchedule

24 hours/day, 7 days/week, 52 weeks/yr

Air Stripping

1

10

100

1000

10 4

10 100 1000 10 4

MTBE Only

MTBE with Other VOCs

Flow

rate

(gal

/min

)

MTBE Concentration (ppb)

No off-gas treatment needed

MTBE Concentration (ug/L)

Flow

rate

(gal

/min

)

Air Stripping

-5

-4

-3

-2

-1

3.0E-03 3.1E-03 3.2E-03 3.3E-03 3.4E-03 3.5E-03

1/T (K)

ln(H

) (d

imen

sion

less

)

Robbins et al., 1993

VP-Solubility Method

Method of Rinker & SandallSPME/GC/MS Method

Air Stripping

0

20

40

60

80

100

120

140

5 10 15 20 25 30 35 40 45

Temperature (oC)

Pac

ked

heig

ht (m

)

Cases 1,2,3,7

Cases 4,8

Cases 5,9

Cases 6,10

Effluent Concentration = 5 ppb

Air Stripping

Case 1 2* 3* 4* 5 6 7* 8* 9* 10*Concentration (ug/L ) 100 100 100 500 1000 5000 100 500 1000 5000

Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10MTBE Effluent at 5 ug/L

No air treatment 0.23 0.25 0.40 0.59 0.68 0.88 1.54 2.30 2.65 3.55Thermal Oxidation w/o heat

recovery0.56 0.62 0.93 1.17 1.28 1.54 3.07 3.56 3.96 5.92

Thermal Oxidation with heatrecovery

0.50 0.53 0.76 0.84 0.88 0.97 2.35 2.68 2.84 3.22

GAC for air treatment 0.66 0.70 1.08 1.58 1.86 2.81 2.90 4.37 5.14 7.45Gas Phase Biofilter for air

treatment0.33 0.41 0.73 0.97 1.07 1.33 3.51 4.60 5.11 6.42

Benzene Effluent at 1 ug/LBenzene (no air treatment) 0.16 0.17 0.29 0.38 0.42 N.A. 1.08 1.36 1.47 N.A.

Air Stripping Treatment Costs ($/1000 gal)

Granular Activated CarbonFlow Diagram for GAC with Steam Regeneration

GACTank

GACTank

GACTank

Condenser Decanter

1

4

5

2

3

6

7

8

1. Influent water + MTBE2. Treated water3. Saturated steam4. MTBE + water vapors5. Condensed MTBE + water6. MTBE (liquid)7. Water with dissolved MTBE8. Treated water

Normal Operation Regeneration 1st Tank

Legend1

MTBE Storage

GAC

Cs = 11.699 Cw0.7101

r2 = 0.9987

0.01

0.10

1.00

10.00

0.0001 0.0010 0.0100 0.1000 1.0000

MTBE Concentration, Cw (mg/L)

Equ

ilibr

ium

GA

C C

once

ntra

tion,

Cs

(mg/

g)Equilibrium Adsorption Isotherm for MTBE on GRC-22

data from Calgon Carbon Corporation, 1998

GAC

Case 1 2 3 4 5 6 7 8 9 10Concentration (ug/L ) 100 100 100 500 1000 5000 100 500 1000 5000

Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10Low organics, replace GAC 0.65 0.66 0.93 1.43 1.77 3.07 1.20 1.81 2.24 3.85High organics, replace GAC 0.74 0.76 1.03 1.65 2.08 3.77 1.32 2.09 2.62 4.71Low organics, regenerateGAC

0.34 0.38 0.55 0.81 0.98 1.67 1.98 2.25 2.50 3.29

High organics, regenerateGAC

0.39 0.44 0.61 0.93 1.15 2.05 2.18 2.60 2.92 4.02

Benzene, low organics,replace GAC

0.17 0.18 0.42 0.43 0.43 N.A. 0.57 0.58 0.59 N.A.

GAC Treatment Costs ($/1000 gal)

Advanced Oxidation

ln k = -5253.5/T + 23.952r2 = 0.9483

5.5

6

6.5

7

7.5

0.0031 0.0032 0.0033 0.00341/T (K-1)

ln k

(M-1

s-1

)Temperature Dependence of MTBE Oxidation with Ozone

Advanced Oxidation


Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10Reactor Volume (gal) 1000 500 200 500 500 1000 100 100 100 200Number of Reactors 3 3 2 2 2 3 1 2 2 2

Ozone Production (kg/hr) 0.25 0.12 0.025 0.12 0.25 1.24 0.003 0.012 0.025 0.12

AOP Operating Conditions

Advanced Oxidation


Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10Only Ozone 0.29 0.41 1.17 1.52 1.68 3.48 3.55 4.19 4.19 5.78

Ozone + GAC 0.67 0.75 1.44 1.95 2.14 3.45 5.99 6.02 6.05 7.25UV/Hydrogen Peroxide 0.62 0.65 1.30 1.35 1.40 1.83 3.15 3.20 4.01 4.06

Ozone/H2O2 studies under way

AOP Treatment Costs ($/1000 gal)

Hollow Fiber Membranes

Water Inlet Port Water Outlet PortHollow Fiber

(Bundle may have 100 to 10,000 fibers)

Shell End-Plate

Potting Material(typically Epoxy)

Module ShellVapors/Gases Outlet Port

Controlled Air Inlet Port

Typical Hollow Fiber Membrane Model Construction


Lumen

Typical wall thickness:10-50 mm

Inside diameter: 90-450 mm

Outside diameter: 100-500 mm

Typical porosity: 10-80%Pore size: 0.01 to 0.1 mm

Hollow Fiber cross-sectional view

Hollow Fiber MembranesHollow Fiber Membrane Process Diagram

Water Pump

Hollow FiberMembrane Module

VacuumPump

Air/Gas inlet

Regulating Valve

TreatedWater Effluent

InfluentWater with

Organics

Vacuum Gauge

Adsorption,Catalytic or

Thermal Oxidation

Hollow Fiber MembranesComparison between theoretical and experimental

removal efficiency for Hollow Fiber Membrane

y = 1.006x - 0.0045r2 = 0.9464

0%

20%

40%

60%

80%

100%

0% 20% 40% 60% 80% 100%

Experimental Removal Efficiency

Theo

retic

al R

emov

al E

ffici

ency

Hollow Fiber MembranesPredicted performance for commercial membrane

50%

60%

70%

80%

90%

100%

10 15 20 25 30 35 40

Temperature (oC)

Theo

retic

al R

emov

al

10 gpm

15 gpm

20 gpm



Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10MTBE (no air treatment) 0.69 0.72 0.78 0.78 1.16 1.16 1.05 1.05 1.46 1.46MTBE (with air treatment) 1.05 1.12 1.35 1.66 2.25 3.05 1.91 2.29 2.96 3.96Benzene (no air treatment) 0.69 0.72 0.78 0.78 1.16 N.A. 1.05 1.05 1.46 N.A.

HFM Treatment Costs ($/1000 gal)

Comparative Cost Study

1 2* 3* 4* 5 6 7* 8* 9* 10*Concentration (ug/L ) 100 100 100 500 1000 5000 100 500 1000 5000

Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10Air Stripping

MTBE (no air treatment) 0.23 0.25 0.40 0.59 0.68 0.88 1.54 2.30 2.65 3.55MTBE (with air treatment) 0.33 0.41 0.76 0.84 0.88 0.97 2.35 2.68 2.84 3.22

GACMTBE w/low organics 0.34 0.38 0.55 0.81 0.98 1.67 1.20 1.81 2.24 3.85MTBE w/high organics 0.39 0.44 0.61 0.93 1.15 2.05 1.32 2.09 2.62 4.71

AOPOzone only 0.29 0.41 1.17 1.52 1.68 3.48 3.55 4.19 4.19 5.78

Ozone + GAC 0.67 0.75 1.44 1.95 2.14 3.45 5.99 6.02 6.05 7.25UV/Hydrogen Peroxide 0.62 0.65 1.30 1.35 1.40 1.83 3.15 3.20 4.01 4.06

Hollow Fiber MembraneMTBE (no air treatment) 0.69 0.72 0.78 0.78 1.16 1.16 1.05 1.05 1.46 1.46MTBE (with air treatment) 1.05 1.12 1.35 1.66 2.25 3.05 1.91 2.29 2.96 3.96*air treatment may not be required for this system.

Treatment Costs ($/1000 gal)

Unit Water Treatment CostTotal Groundwater Site Remediation

Gasoline withMTBE

ConventionalGasoline

Range Typical Range TypicalSite

investigation$30,000 -250,000

$100,000 $20,000-170,000

$77,000

SoilRemediation

$22,000 -260,000

$97,000 $22,000-260,000

$97,000

Watertreatment

$140,000-240,000

$190,000 $55,000-180,000

$110,000

Total $190,000-750,000

$390,000 $97,000-610,000

$280,000

AnnualizedCost

$95,000-150,000

$130,000 $50,000-120,000

$93,000

Groundwater ContaminationAggregate Annualized Cost of UST Treatment

Gasoline with MTBE Conventional GasolineNumberof sites

90% fullremediation

10%natural

attenuation

20% fullremediation

80% naturalattenuation

Older activeUSTs

350 $60 to 240million

$2 to 11million

$7 to 44million

$13 to 70million

Older USTsites

2100 $360 to1,420million

$40 to 160million

$42 to 270million

$81 to 420million

Subtotal 2450 $420 to1,660million

$42 to 170million

$49 to 310million

$94 to 490million

Annualupgraded

tank failures30-880

$15 to 590million

$2 to 68million

$2 to 110million

$8 to 180million

Aggregate Annualized Cost ofWater Treatment1

Low Estimate High EstimateOlder UST sites $320 million $1030 millionFuture UST sites $7 million $370 million

Pipelines $5 million $10 millionPublic Wells $2 million $36 millionPrivate Wells $1 million $4 million

Surface Water $4 million $30 millionTotal $340 million $1,480 million

1relative to conventional gasoline

Conclusions

z Unit Water Treatment Costs for MTBE are40 to 100% greater than for commongasoline components (e.g. BTEX)z MTBE will be at much higher

concentrations than other componentsz Site characterization and remediation

costs are higher for MTBE than BTEX,given the greater extent of contamination

Conclusions

z Natural attenuation is less likely to be anoption due to the low biodegradability ofMTBE under natural conditionsz UST failures in past, present and future

place groundwater supplies at risk;immediate remediation is cheaperz Legacy of MTBE is treatment costs of

hundreds of millions of dollars per year untilthe sources are removed

Acknowledgements

z Study funded under SB 521 through UCToxic Substances Research & TeachingProgramz Contributions fromyE. Schroeder et al. (1998): biofiltrationyM. Suffet et al. (1998): activated carbonyS. Hitz, H. Kun, A. Peterson, B. Smith & M.

Yoshioka, graduate students at the BrenSchool

MTBE treatment.pdf

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