Paul ChuEUEC ConferenceFebruary 1, 2012
EPA’s Effluent GuidelinesPotential Impact on Coal Plants and EPRI R&D
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Agenda
•Cross-Media Transfer of Pollutants•EPA and other regulatory activities•EPRI R&D
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Cross Media Transfer of Volatile ElementsIncluding Hg, Se
WetFGD
Stack
ESP
Boiler
SCR
Pond
Hg, Se Hg Se
Hg, Se
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Issue: Mercury, Selenium in FGD Wastewater
• CAIR, CAVR, CAMR, MATS – many new FGDs being installed
• Volatile elements, e.g. mercury (Hg), selenium (Se) captured in the FGD, and may be present in blowdown/wastewater
• New FGDs may be required to treat the blowdown/wastewater
• Some states, regions regulating mercury at 1.3 to 12 ppt, as well as selenium
• Capital costs: $25-50M to >$100M, depending upon treatment approach
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EPA Effluent Guidelines (ELG) Activities
• Fall ’09, EPA announced its plans to select the steam electric industry, and issued final report
• EPA issued ICR questionnaire in June ’10• EPA conducted sampling/analytical studies at 7
FGD water treatment systems • EPA Effluent Guideline Revisions
– How broad, stringent?– What water streams, target pollutants
• Proposed rule: by July 2012 – Final rule: by Jan 2014
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Possible Wastewater LimitsWhere could EPA go??
• FGD wastewater: Hg, Se, and others at FGD wastewater treatment system effluent
• Fly ash (and bottom ash) transport water
– Potentially no discharge
• CCR landfill leachate
– Chemical precipitation
• Metal cleaning wastes and turbine wash water
– Guidelines for management
• Cooling water discharges
– Restrict discharge of biocides
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PSNH Merrimack: Draft Permit
• FGD and water treatment system coming online• EPA Region 1 recently issued a draft permit for FGD
and other wastewater discharges• http://www.epa.gov/region1/npdes/merrimackstation/• EPA (DC headquarters) also provided input
– Concluded phys/chem + biological as BAT• Comments due February 28, 2012
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Proposed Merrimack FGD Wastewater Limits
Daily Maximum Monthly Average
Arsenic (ppb) 15 8Chromium (ppb) 10 -Copper (ppb) 16 8Mercury (ppt) * 55 22Selenium (ppb) 19 10Zinc (ppb) 15 12
* Supporting document (Attachment E) notes 14 ppt daily maximum ?
Weekly sampling requirements using “sensitive” methods, ICP-MS-CRC
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EPA Sampling/Analytical StudiesFocus on FGD Water Treatment
• EPA conducted studies at 7 FGD water treatment systems – Physical/Chemical (4)– Physical/Chemical + Biological (3)
• Focus on trace metal, nutrients• Short-term (4 days) studies• EPA requested all 7 sites conduct 4
additional sampling events
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EPA Effluent Guidelines ICR: 9 PartsCompleted in Fall 2010
• A – Plant Operations• B – FGD• C – Ash Handling• D – Ponds/Water Treatment• E – Metal Cleaning Wastes• F - Ponds/Landfills• G – Leachates (includes sampling)• H – Nuclear• I - Finances
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EPA “BAT” Water Treatment EvaluationBAT – Best Available Technology
• EPA considering 3 approaches:– Physical/chemical – Physical/chemical + biological (i.e.
GE ABMet)– Zero Liquid Discharge (ZLD)
• Costs consideration• Pollutant removal • EPRI conducting parallel evaluation
to help inform the rulemaking
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EPRI ICR Data Analyses Project
• Request power plants send non-CBI data to EPRI, in parallel with EPA
• EPRI data analyses focus on FGD water– Cost/benefit analyses, extrapolating the
available data to broader industry – FGD water treatment cost estimates– Estimate pollutant removed
• Review ICR data to understand other water management issues
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FGD Water Treatment: Objectives
• Evaluate technologies:– Mercury: 1-10 ppt– Selenium: 10-100 ppb, including all
species• Provide as many solutions as possible
– Physical/chemical– Biological– Zero liquid discharge, i.e. thermal
evaporation
Cost-effective, reliable technologies needed
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• Mercury present in FGD water at concentrations of about 1 part-per-billion
• Louisiana Superdome holds ~1 trillion ping-pong balls
• 1 ppb = 1000 “mercury” balls
• 1 ppt = 99.9% mercury capture: find and remove 999 of 1000 mercury ping-pong balls (among the trillion other ping-pong balls)
Louisiana Superdome
Measuring, Capturing Mercury (and other elements) are a Challenge!
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EPRI R&D: Managing Mercury/Seleniumin FGD Water Discharges
Develop/validate analytical techniques
Characterize sources
Treatment• Phys/Chem• Biological• Passive• Others?
FGD chemistry• Chemistry to avoid• Role of organic acids
Guidelines for managing Hg/Se in FGD discharge
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Variability: What are the drivers?Data from Biological Reactor
• Mercury concentrations “spike” at inlet and effluent• Inlet selenium concentrations spike, but effluent constant
2x increase
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Characterization: Mercury, SeleniumImpact on Treatability
• Mercury– Particulate, sub-micron, and dissolved– Likely bound with other ligands, i.e. organics,
halides, sulfur, selenium• Selenium
– Speciation: Se+4, Se+6 (more challenging to remove), “other” Se compounds
– Oxidation/reduction potential (ORP), pH, iron (Fe), manganese (Mn): likely factors
R&D Need: Understand and manage Hg/Se Chemistry
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EPRI Water Treatment StudiesLab, pilot as well as full-scale evaluations• Physical/Chemical Approaches
– Challenges to reach Hg/Se objectives– Metallic Iron cementation– Iron/Sulfide + microfiltration – Microfiltration + adsorption– Hybrid zero-valent iron (ZVI)
• Biological Approaches– Generally better Hg/Se removals– GE ABMet bioreactor (full-scale)– Vertical flow “wetland”
• Several pilots, full-scale
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Thermal ZLD Treatment SystemsBrine concentrator, crystallizer
• Inability to discharge wastewater• Costs: capital and operating costs• Thermal evaporation = energy• Alternative: chemical softening
– Reduces energy consumption– Trade-off: “Chemical plant”
• Reliability– Scaling, corrosion– Materials of construction
• Solids disposal
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Other Possible Wastewater Issues
• Fly ash (and bottom ash) transport water
– Potentially no discharge
• CCR landfill leachate
– Possible water treatment
• Metal cleaning wastes and turbine wash water
– Possible guidelines for management
• Cooling water discharges
– Possible restriction of discharge of biocides, priority pollutants
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Many Challenges AheadWhere are we going??
"If you don't know where you are going, you might not get there."
• Federal and state/regional drivers• Mercury/Selenium (current focus)
– Phys/chem vs biological/wetlands– Nutrients: biological/wetlands favored– Bromide, Chloride TDS?– ~1 ppb arsenic? Boron? Bromide?– Thermal Zero Liquid Discharge (ZLD)?
• Focus on Hg, Se….or do it “all”?• Other issues, i.e. ash transport waters and
other plant wastewaters