EPAâ€™s Effluent Guidelines - EPRI | Home

Paul ChuEUEC ConferenceFebruary 1, 2012

EPA’s Effluent GuidelinesPotential Impact on Coal Plants and EPRI R&D

2© 2012 Electric Power Research Institute, Inc. All rights reserved.

Agenda

•Cross-Media Transfer of Pollutants•EPA and other regulatory activities•EPRI R&D


Cross Media Transfer of Volatile ElementsIncluding Hg, Se

WetFGD

Stack

ESP

Boiler

SCR

Pond

Hg, Se Hg Se

Hg, Se


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


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


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


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


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


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


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


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


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


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


• 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!

http://www.healthy-oil-planet.com/images/mercury1.jpg


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


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


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


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


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


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


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


Together…Shaping the Future of Electricity

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