Treatment of Contaminated SedimentTrudy Estes, P.E., Ph.D. and Daniel Averett, P.E.

US Army Corps of Engineers Engineer Research and Development Center

Vicksburg, MS

Who do we think we are!?• ERDC

– Provides technical support to USACE Districts & other agencies

– Address the gap between concept and application

• We are NOT – Marketing treatment– Pro or con treatment

• Our interest– Alternative to upland disposal– Objective, independent evaluation

of viable technologies

• Our focus– Typically navigation dredging– Large volumes, long term– Not highly contaminated– Treatment must compete

with confined disposal– WRDA focus – <$40/yd3 cost

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CV’s• Trudy J. Estes

– BS Civil Engineering– MS Environmental Engineering– PhD Civil/Environmental

Engineering– P.E. State of Mississippi– ERDC Research Civil Engineer

• Environmental Lab• Sediments team• 1992 – present

– Physical separation of firing range soils

– New Bedford Harbor dewatering– Contaminant distribution in

sediments– Estes et al 2011

• Daniel E. Averett– BS Chemical Engineering– MS Environmental Engineering– P.E. State of Mississippi– ERDC Research Civil Engineer

• Environmental Lab• Sediments team• 1984 – present

– Rocky Mountain Arsenal– New Bedford Harbor– WRDA 1990, 1992 – ARCS program– Estes et al 2011

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Estes et al.

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Topics• Type of treatment technologies

– Target contaminants

– Issues

– Demonstrated scale

• General considerations– Challenges

– Technology selection

• Processing specifics– Mechanisms of treatment

– Understanding effectiveness/efficiency

– Logistical challenges

– Cost considerations

– Uncertainty

– Sediment demonstrations5

TREATMENT TYPES

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What is treatment?There are multiple definitions….

• Legal/regulatory definitions

• Public perception

• Risk reduction

And also….

• Ex-situ vs. in-situ processes

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Primary Treatment Types

• Separation– Volume reduction– Solids size & density

separation

• Soil washing– Separation– Phase transfer – Oxidation

• Stabilization– Physical or chemical

immobilization of contaminants

• Contaminant destruction– Incineration– Chemical oxidation– Vitrification

• Biological?– Composting

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Physical Separation

• Separation of solids– Size

– Density

• Target Contaminants

– Metals

– Organic compounds

• No contaminant destruction

• Separate fractions for appropriate management

– Pretreatment

– Disposal/Beneficial use

• Wet and dry processes

Coarse fraction

Organic detritus

Fine fractionCarbonaceous

materialsHigh surface area silts and clays

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Soil Washing

• Variation of physical separation– Wet process

– Surfactants/dispersants

– Extracting/chelating agents

– Oxidizing agents

• Issues– Large wastewater stream

– Residual sediment fractions requiring disposal

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Solidification/Stabilization

• Amendments– Solidify matrix– Immobilize contaminants

• Target contaminants– Metals– Organic contaminants

• Contaminant destruction– Organics – limited to none– Metals - none

• Typically ex-situ– Dewatering

• In-situ processes exist• Current research

– Carbon injection/capture of dissolved fraction

Hunter’s Point – ESTCP carbon injection demonstrationFrom: Ghosh, Luthy, Zimmerman, McLeod, Smithenry, Bridges and Millward 2004

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In-barge mixing of sediment and “cement”

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Chemical Oxidation• Addition of Reagents

– Contaminant destruction

– Goal - mineralization to CO2 + H2O

• Target - organic compounds

• Additives

– Potassium permanganate

– Hydrogen peroxide

– Sodium persulfate

– Fenton’s reagent

– Ozone

– Dissolved oxygen

– Proprietary mixtures

• Issues– Corrosive/explosive

chemicals

– Non-specific to contaminants

– Intermediate products

– Limited effectiveness ex-situ in sediments

– In-situ unlikely to be successful

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Thermal Technologies

• Heating processes– Destroy organics– Immobilize metals

• Target contaminants– Low temp – volatiles– High temp – all

contaminants

• Processes– Volatilization– Incineration (organics)– Vitrification/immobiliza

tion (metals)

• Issues– Public resistance– Energy intensive– High capital cost– Not mobile– Limited demonstrated

scale– Processing equipment

issues?

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Biological Treatment

• Target contaminants– Organic compounds

• Processes– Composting

– Bioreactors

– In-situ?

• Issues– Lengthy process

– Recalcitrant compounds –aromatics (PAHs, PCBs)

– Difficult in-situ

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GENERAL CONSIDERATIONS

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Major Challenges in Sediment Treatment

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• Heterogeneity

– Complex matrix –operationally challenging

– Characterization & treatment verification difficult

• Fine grained– Very difficult to treat

• Organic content• Multiple contaminants

– Heavy metals– Inorganics– PAHs1

– PCBs2

– Pesticides– Dioxins– Nutrients

1) Polycyclic aromatic hydrocarbons, 2) Polychlorinated biphenyls

Major Challenges in Sediment Treatment

• Operational limitations– Access– Current– Traffic– Water depth– Complete removal

• Debris impacts– Dredging costs– Dredge/bucket type– Cleanup and disposal

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• Water

– Sediment water content

– Produced water

• Cost– And cost uncertainty

Scale of Sediment Demonstrations(in-situ cubic yards)

………….. 199

4

199

6

199

9

20

00

20

01

20

03

20

04

20

05

20

06

20

07

(in-situ cubic yards)

Rotary Kiln 4

Cement Lock 3 44

Minergy 16

Biogensis 30 700 330 14.6K X

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Th

erm

al

Physical/Chemical Sediment Washing

Dewatering

Thickening

Water treatment

Size/density separation

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• 200 m³ an hour capacity• 8 18 m3 membrane filter presses (59’ x 70’ each)• 9,000 m² for the mechanical section

Boskalis Dolman Fox River Plant

Supporting 8”-12” dredge operations

• Failure of technology developers to consider the “integrated” treatment train

ResidualsPretreatmentProcess

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Technology Selection Criteria

• Suitability – Sediment properties– Target contaminants– Processing goals

• Efficiency– Degree of treatment or

risk reduction required• Pretreatment

requirements• Residual process

streams• Capacity and scalability

• Cost/economics– Capital cost vs. sediment

volume– Sustained vs. short term

operations• Mobility• Technology maturity• Product market?

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Rotary kiln

Decontamination efficiency

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(Mass)

Contaminant mass in treated vs. untreated sediment

Rotary kiln

Overall Process Efficiency

24Total output vs. total input

Rotary kiln

Stage Efficiency

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“where in the process” treatment is occurring…..

PERFORMANCE

Physical Separation

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Physical Separation

• Mature technologies• Adapted from mining

industry• Sediment applications

– Saginaw & Green Bay (demos)

– Miami River (full scale)– Fox River (full scale)– Erie Pier (Duluth/Superior

Harbor)27

Miami River Project

• 2004-2008• 5.5 mile reach• Modular, containerized

plant• 8.5 Acre staging area• 550,000 yd3 cubic

yards– Silty/fine sand– Discontinuous clay

lenses– Mechanical dredging

• Debris– Tires, boats, cars,

motorcycles, heavy industrial debris, trash

– Unexploded munitions

• Overall project cost– $80M

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Photograph of Boskalis-Dolman vibrating screens,hydrocyclones, and washing system, Miami River,FL (Courtesy Bastiaan Lammers, Boskalis Dolman)

PERFORMANCE

Soil Washing

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Biogenesis1

• Physical/chemical treatment processes

• Organics treatment– Phase transfer

– Size separation

– Chemical oxidation

– Filtration

– Carbon adsorption

• Metals treatment– Phase transfer/

Chelation

– Size separation

– Filtration

– Carbon adsorption

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1) Physical/chemical processes utilizing separation of a sediment slurry coupled with various chemical treatments, are consistent with our operational definition of soil washing; the process is characterized by the technology developer simply as a “physical/chemical” process.

Biogenesis

• Beneficial use product– Topsoil component

• Pretreatment– Debris removal– Screening

• System inputs– Sediment– Water– Surfactants– Oxidizers– Chelants– Polymers

• System outputs– Debris– Wastewater1

– Fine grained solids– Treated sediment

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1) Recent generations include WW treatment

Apparent Loss/Treatment Mechanisms NY/NJ Harbor Demo1

• Metals– Phase transfer to

wastewater (WW)

– Particulate losses to WW

– Mercury volatilization

• Organics– Material losses Pre-

Treatment

– Limited transfer to WW

– Chemical oxidation?

– VOCs volatilization

1) Not the most recent plant configuration

PERFORMANCE

Thermal Technologies

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Minergy

• Glass furnace technology• Oxygen & natural gas

fueled• Glass aggregate product• Primary present

application sewage sludge treatment

• Commercial scale plants generating trench fill for municipalities

• Most sediments have suitable mineralogy

• Salinity can be problematic (corrosive)

• Process– Oversize & metallic debris

removal – Dewatering (<50% MC)– Drying (<10% MC)– Flux addition– Melting (1600 deg C) – 6

hr residence time– Quenching– Offgas capture & treatment

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Cement Lock1

• Rotary kiln technology

• 2 beneficial use products– Ecomelt (cement

additive) – slagging or vitrification

– EcoAggMat (aggregate) – non-slagging or sintering

• Process– Debris and oversize

(>2in) removal– Dewatering– Drying– Modifiers– Kiln treatment (1400-

1500 deg C)– Quenching– Offgas capture &

treatment

1) Volcano Partners

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Process Residuals

• Pretreatment & offgases• Contaminants present in sediment• Breakdown products

– Chlorine– Dioxins (from PCBs incineration)– Halogens– Ammonia– SOx, NOx, CO, H2S– Particulates

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COSTS

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Treatment Cost Comparisons

• Highest uncertainty

• Non-uniform basis– Process scale

– Capital recovery period

– Total volume treated

– Potential costs may not have been considered

– Value of beneficial use products may/may not have been included

• Extrapolated from small-scale operations– Real cost of full scale

processing unknown

• Cost may be contingent upon– Guaranteed total or

annual volume

– Extended performance period (eg. 20 years)

– Assumed product value

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Normalized Cost Estimates1

Rotary Kiln

Cement Lock

Minergy BiogenesisSM

Volume Basis (m3) 380,000 380,000 380,000 430,000

Volume Basis of Cost Data (yd3)

500,000 500,000 500,000 560,640

Yrs Straight Line Depreciation 10 20 15 10

Sale of Product $35.76 $41.81 $0.91 $11.30

Sale of Energy NA $19.56 NA NA

Total Cost $91.82 $101.16 $71.75 $51.99

Net Cost $56.06 $39.79 $70.84 $40.69

1) 2009 basis, subject to some uncertainty, typically 30 to 50% under actual cost and as much as 30% over actual for preliminary design

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CONCLUSIONS

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General Observations

• Most have success “potential” – Depending on

processing objectives– Economic “fit”

• Obstacles– Uncertainty in resolution

of pilot scale “issues”– Undemonstrated

sustained, full scale ops– Cost & cost uncertainty– Market uncertainty

• Significant technical development in recent years– Ready for “next steps”

with adequate supporting mass balance data from site-specific pilot

– Risk involved in being first full scale operation

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Treatability & Process Selection

• Bench & pilot testing

– Realistic feasibility evaluations

– Must support mass balance for all materials and contaminants

• Process efficiency

– Highest decontamination efficiency ≠ highest overall efficiency

– All processes produce some residuals - $$

– Consider processing objectives

• Is high decontamination efficiency needed?

• Regulatory requirements?

• Some constituents may persist or be leachable even with high efficiency processes

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QUESTIONS ???

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