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
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199
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199
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20
00
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03
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(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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