Treatment of
Contaminated Sediment
Trudy 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
• Our focus
– Provides technical support to
USACE Districts & other agencies
– Address the gap between concept
and application
• We are NOT
– Marketing treatment
– Pro or con treatment
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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• Our interest
– Alternative to upland disposal
– Objective, independent evaluation
of viable technologies
2
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
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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
3
Estes et al.
4
Topics
• Type of treatment technologies
– Target contaminants
– Issues
– Demonstrated scale
• General considerations
– Challenges
– Technology selection
• Processing specifics
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Mechanisms of treatment
Understanding effectiveness/efficiency
Logistical challenges
Cost considerations
Uncertainty
Sediment demonstrations
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TREATMENT TYPES
6
What is treatment?
There are multiple
definitions….
• Legal/regulatory definitions
• Public perception
• Risk reduction
And also….
• Ex-situ vs. in-situ processes
7
Primary Treatment Types
• Separation
– Volume reduction
– Solids size & density
separation
• Soil washing
– Separation
– Phase transfer
– Oxidation
• Contaminant
destruction
– Incineration
– Chemical oxidation
– Vitrification
• Biological?
– Composting
• Stabilization
– Physical or chemical
immobilization of
contaminants
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Physical Separation
• Separation of solids
– Size
– Density
Carbonaceous
materials
Fine
fraction
High
surface
area silts
and clays
• Target Contaminants
– Metals
– Organic compounds
• No contaminant destruction
• Separate fractions for appropriate
management
– Pretreatment
Coarse
– Disposal/Beneficial use
fraction
• Wet and dry processes
Organic
detritus
9
Soil Washing
• Variation of physical separation
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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
• In-situ processes exist
• Current research
– Carbon injection/capture
of dissolved fraction
– Metals
– Organic contaminants
• Contaminant destruction
– Organics – limited to none
– Metals - none
• Typically ex-situ
– Dewatering
Hunter’s Point – ESTCP carbon injection demonstration
From: Ghosh, Luthy, Zimmerman, McLeod,
Smithenry, Bridges and Millward 2004
11
In-barge mixing of
sediment and “cement”
12
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 exsitu in sediments
– In-situ unlikely to be
successful
13
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
• Organic content
• Multiple contaminants
– Heavy metals
– Inorganics
– PAHs1
– PCBs2
– Pesticides
– Dioxins
– Nutrients
• Heterogeneity
– Complex matrix –
operationally
challenging
– Characterization &
treatment verification
difficult
• Fine grained
1) Polycyclic aromatic hydrocarbons,
2) Polychlorinated biphenyls
– Very difficult to treat
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Major Challenges in Sediment
Treatment
• Operational limitations
– Access
– Current
– Traffic
– Water depth
– Complete removal
• Debris impacts
– Dredging costs
– Dredge/bucket type
– Cleanup and disposal
• Water
– Sediment water content
– Produced water
• Cost
– And cost uncertainty
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2007
2006
2005
2004
2003
2001
2000
1999
1996
…………..
1994
Scale of Sediment Demonstrations
(in-situ cubic yards)
Thermal
(in-situ cubic yards)
Rotary Kiln
4
Cement Lock
3
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Minergy
Biogensis
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30
700
Physical/Chemical Sediment
Washing
330
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14.6K
X
Boskalis Dolman Fox River Plant
• 200 m³ an hour capacity
• 8 18 m3 membrane filter presses (59’ x 70’ each)
• 9,000 m² for the mechanical section
Supporting
8”-12”
dredge
operations
Size/density separation
Dewatering
Water treatment
Thickening
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• Failure of technology developers to
consider the “integrated” treatment
train
Residuals
Pretreatment
Process
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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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Decontamination efficiency
Rotary kiln
(Mass)
Contaminant mass in treated vs. untreated
sediment
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Overall Process Efficiency
Rotary kiln
Total output vs. total input
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Stage Efficiency
Rotary kiln
“where in the process” treatment is occurring…..
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Physical Separation
PERFORMANCE
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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)
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Miami River Project
• 2004-2008
• 5.5 mile reach
• Modular, containerized
plant
• 8.5 Acre staging area
• 550,000 yd3 cubic
yards
• Debris
– Tires, boats, cars,
motorcycles, heavy
industrial debris, trash
– Unexploded munitions
• Overall project cost
– $80M
– Silty/fine sand
– Discontinuous clay
lenses
– Mechanical dredging
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Photograph of Boskalis-Dolman vibrating screens,
hydrocyclones, and washing system, Miami River,
FL (Courtesy Bastiaan Lammers, Boskalis Dolman)
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Soil Washing
PERFORMANCE
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1
Biogenesis
• Physical/chemical
treatment processes
• Organics treatment
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Phase transfer
Size separation
Chemical oxidation
Filtration
Carbon adsorption
• Metals treatment
– Phase transfer/
Chelation
– Size separation
– Filtration
– Carbon adsorption
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.
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Biogenesis
• Beneficial use product
– Topsoil component
• Pretreatment
– Debris removal
– Screening
• System outputs
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Debris
Wastewater1
Fine grained solids
Treated sediment
• System inputs
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Sediment
Water
Surfactants
Oxidizers
Chelants
Polymers
1) Recent generations
include WW treatment
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Apparent Loss/Treatment
Mechanisms NY/NJ Harbor Demo1
• Metals
– Phase transfer to
wastewater (WW)
– Particulate losses to WW
– Mercury volatilization
• Organics
– Material losses PreTreatment
– Limited transfer to WW
– Chemical oxidation?
– VOCs volatilization
1) Not the most recent plant
configuration
Thermal Technologies
PERFORMANCE
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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) – nonslagging or sintering
• Process
– Debris and oversize
(>2in) removal
– Dewatering
– Drying
– Modifiers
– Kiln treatment (14001500 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
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• 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
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
Yrs Straight Line Depreciation
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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