Emerging Contaminants and Planning For Water Treatment Needs … · Not a case study . . ....
Transcript of Emerging Contaminants and Planning For Water Treatment Needs … · Not a case study . . ....
OBG PRESENTS:
Emerging Contaminants and Planning For Water Treatment NeedsApril 10, 2018
Overview
▪ Not a case study . . .
▪ Traditional drinking water treatment objectives
▪ Contaminants of emerging concern▪ Definition, examples, sources, leading treatment technologies
▪ Thoughts, issues, planning approach
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Traditional drinking water treatment objectives
▪ Largely dictated by regulations – public health and aesthetics
▪ Kill or inactivate disease-causing organisms
▪ Remove particles
▪ Improve “aesthetic” characteristics – clarity, taste, odor, hardness, iron, manganese, etc.
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Traditional drinking water treatment objectives (cont’d)▪ Reduce corrosivity
▪ Reduce naturally occurring organic constituents (NOM, TOC)
▪ Minimize byproducts of chemical disinfection
▪ Improve dental health
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Typical drinking water treatment system
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Contaminants of Emerging Concern
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Contaminants of emerging concern defined
▪ [USEPA] “. . . a chemical or material characterized by a perceived, potential or real threat to human health or the environment or by a lack of published health standards. A contaminant may be ‘emerging’ because of the discovery of a new source or a new pathway to humans.”
▪ [USGS] “. . . any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological and/or human health effects. In some cases, release of emerging chemical or microbial contaminants to the environment has likely occurred for a long time, but may not have been recognized until new detection methods were developed. In other cases, synthesis of new chemicals or changes in use and disposal of existing chemicals can create new sources of emerging contaminants.”
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Common characteristics of emerging contaminants
In the news
Often with another contaminant, in a commercial product, or a breakdown product
Not on typical analyte lists . . . requires special analytical procedures/methods
Limited science on health/ecological effects (or limited agreement on results)
No enforceable standards; no, limited or changing guidance values/health advisories
Widespread occurrence . . . but limited fate/transport info
Limited information on treatment technologies
New acronyms
Categories and examples
Naturally occurring• Algal toxins
Man-made• Perfluorinated compounds• 1,4-Dioxane• Pharmaceuticals• Personal care products• Endocrine disrupting compounds
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UCMR3 sampling of PWSs in 2013-20151,4-Dioxane detected >0.35 ug/L in 6.9% of PWSs
PFOS/PFOA detected >70 ng/L in 0.9%/0.3% of PWSs
Regulatory framework
Contaminant Candidate List (CCL) Unregulated Contaminant Monitoring Rule
(UCMR) Health Advisories (HA)
Federal
Inconsistent guidelines Proactive States: Lower thresholds, invites
litigation
No Federal Water Standards
Default to States
Contaminant Candidate List (CCL)
Statutory requirements under EPA Safe Drinking Water Act (SDWA)
EPA to publish CCL every 5 years
EPA to determine whether to regulate at least 5 contaminants from CCL every 5 years
CCL screening and final selection is risk-based
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Contaminant Candidate List By the numbers
CCL1 (1998) 50 chemicals, 10 microbial
contaminants
CCL2 (2005) Carryover from CCL1 (no new) 42 chemicals, 9 microbial
contaminants
CCL3 (2009) Method revamped Considered 6003 chemicals 104 chemicals, 12 microbial contaminants Includes cyanotoxins Includes 1,4-Dioxane and PFOA/PFOS
CCL4 (2016) 97 chemicals, 12 microbial contaminants 2 new, 9 removed from CCL3 Added manganese (CCL1) and nonylphenol
Algal toxins
▪ Cyanobacteria – or blue-green algae – are common, photosynthetic, naturally occurring bacteria
▪ Cyanobacteria produce cyanotoxins – harmful to environment, animals and humans
▪ Many species of cyanobacteria
▪ Most common cyanotoxins are anatoxin-a, microcystin, cylindrospermopsin – but there are more
▪ Cyanotoxins included on CCL4; no enforceable MCL13
Algal toxins, health effects and source bacteria
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Algal blooms
Somewhat predictable Have plagued water treatment plant operators for
decades
Water temperatures
Nutrient loads
Wind
Rainfall
Chlorophyll
Mostly associated with taste and odor issues
MIB and geosmin
Some issues with filter fouling
Algal blooms
What is known What is not known
Blooms are common throughout NYS
All water types are vulnerable
Blooms seem to be more common in lakes with high P & N
Toxin levels are highly variable
Shoreline blooms are much more common
What triggers blooms in lakes with low P & N?
What is role of food web changes? Climate changes?
Invasive species?
How do blooms form in each water body?
NYSDEC/DOH HAB Symposium 3/17 ESF
Algal toxins
▪ Some float on surface, some found in bottom sediments, some disperse within water column
▪ Blooms most common in late summer – but not always
▪ In most cases (i.e., anatoxin-a, microcystin), toxins are intracellular – retained within cell wall
▪ In some cases (i.e., cylindrospermopsin), toxins are extracellular –released by live cells
▪ Not all algal blooms are toxic17
Algal toxins – guidance levels
▪ World Health Organization – 1.0 µg/L
▪ USEPA Drinking Water Health Advisories (2015)
▪ USEPA Water Quality Criteria/Swimming Advisories (12/2016 Draft)
▪ Microcystin – 4.0 µg/L
▪ Cylindrospermopsin – 8.0 µg/L
▪ New York State – none
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Algal toxins
▪ In 2017, 169 New York State water bodies reported suspicious or confirmed toxic algae blooms (up from 61 in 2012 and 131 in 2015)
▪ Includes all Finger Lakes
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Lake Erie – July 19, 2017
Owasco Lake – Sept. 18, 2017
First step: source management
• Alternate source• Alternate intake location/level• Algaecides• Etc.
Consider source management strategies . . .
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Leading treatment technologies – algal toxins
• Where primary concern is intracellularcyanotoxins
• Avoid lysing algal cells – reduce pre-oxidant dosage if possible
• DAF more effective than sedimentation• Solids removal important
Optimize clarification/
filtration
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Leading treatment technologies – algal toxins
• Most effective for microcystin, less effective for other toxins• PAC: >10mg/L, >45 min. contact time typical• GAC: 10-15 min. EBCT typical
Carbon adsorption
• Generally effective• Operational challenges
Membrane filtration (RO/NF)
• May be effective with certain toxins• Operational challengesBiological filtration
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Leading treatment technologies – algal toxins
• Free chlorine, potassium permanganate and ozone most effective• Chlorine dioxide, chloramines not effective• pH, temperature dependent• Higher dose may be required• CT tables published for cyanotoxin oxidation using free chlorine
Chemical oxidation
• Highly effective• UV/H2O2 and Ozone/H2O2• Effective treatment of other compounds
Advanced oxidation
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Algal toxins – effectiveness of various oxidants
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Perfluorinated Compounds
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PFASPoly- and perfluoroalkyl substances
1000s of compounds in multiple families/subfamiliesPerfluorinated – all C in tail bonded with FPolyfluorinated – one or more C in tail not bonded with FCommon aspect is CnF2n+1 moiety
C-F bond 2nd strongest in organic chemistry (behind Si-F)
Properties/behavior vary dramatically
Special analytical methodsEPA Method 537 (LC/MS/MS)
Perfluorooctane sulfonate (PFOS) (C8HF17O3S)AFFFs, Scotchgard and many other products
Perfluorooctanoic acid (PFOA) (C8HF15O2)PTFE production and products (e.g., Teflon, Goretex)
EPA Health Advisory 70 ng/L PFOS+PFOA (May 2016)
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Perfluorinated compounds (PFAS)
CLIENT RECIPIENTS INDUSTRY AVERAGE
CONSUMER PRODUCT USES
Non-stick coatings/fire retardants
Textile treatment for water/stain repellency
Anti-fogging/anti-static treatments
Paints/adhesives
Fluro-elastomers
Personal care products
Sporting equipment
What are they? Primary concerns
Persistent in environment (C-F bond extremely strong) Bio-accumulative in blood,
kidney and liver Mounting evidence of
health concerns at environmental concentrations
Large “class” of compounds (>100 types) Used for many years Wide range of consumer
products Released to air, water, soil
during manufacturing
FEDERAL
6 compounds on CCL since 2009 EPA Lifetime Health AdvisoryPFOA/PFOS 70 ng/L (updated 2016)
PFAS
STATE
NYNone
NJ14 ng/L (PFOA)
Proposed
NJ40 ng/L (PFNA)
Proposed
VT20 ng/L (PFOA)
Leading treatment technologies – perfluorinatedcompounds
• Highly effective, lower cost• Competition with other compoundsActivated carbon
• Highly effective, higher cost• Reject water requires treatment prior to discharge
Membrane filtration (RO/NF)
• Effectiveness varies, lower costAnion exchange
• Limited effectiveness, higher cost• Significant energy requirementsAdvanced oxidation
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1,4-Dioxane
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1,4-Dioxane
Historically, 90% of U.S. production used as stabilizer in chlorinated solvents, mainly 1,1,1-TCA 2-8% typical in 1,1,1-TCA
1,4-Dioxane in spent solvents can be higher
Source: USEPA Fact Sheet on 1,4-Dioxane, 2014
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Other sources of 1,4-Dioxane
In many other things besides 1,1,1-TCA
Source: USEPA Fact Sheet on 1,4-Dioxane, 2014
Products:
• Paint strippers• Dyes• Greases• Varnishes• Waxes
Impurities:• Antifreeze• Aircraft de-icing fluids
Food production:• Food supplements• Food containing resides from packaging adhesives• Food crops treated with pesticides
Solvent/wetting agents:
• Solvent for impregnating cellulose acetate membrane filters
• Wetting and dispersing agent in textile production
Manufacturing:• Purifying agent in pharmaceutical manufacturing• By-product of PET plastic manufacturing
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FEDERAL
On TSCA list since 2012 No Federal Drinking Water Standard
1,4-Dioxane
STATE
NYNone
NH0.25 µg/L
VT0.30 µg/L
MA0.30 µg/L
NJ0.40 µg/L
Leading treatment technologies – 1,4-Dioxane
• UV/H2O2 and Ozone/H2O2 recognized effectiveAdvanced oxidation
• Not proven effectiveAir stripping
• Performance very site specificActivated carbon
• Not proven effectiveMembrane filtration (RO/NF)
• Not proven effectiveBiofiltration
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Other CECs
Antibiotics, analgesics, steroids, beta blockers, illegal drugsPharmaceuticals
Engineered hormones, perfumes, shampoos, micro-beads, etc.
Some known to have estrogenic properties
Personal care products (PCPs)
Artificial chemicals that when ingested can either copy or obstruct hormones and effect body’s normal functioning
Endocrine disrupting compounds (EDCs)
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Other CECs
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Leading treatment technologies – P&PCPs
• UV/H2O2 and Ozone/H2O2Advanced oxidation
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Thoughts, Issues and Planning Approach
Thoughts
▪ Emerging contaminants are emerging faster now . . .
▪ Advances in analytical capabilities are intersecting with scientific interest and public concern
▪ If we look for contaminants at µg/L and ng/L levels, we are likely to find some
▪ Regulatory standards, advisories and guidance criteria are lacking for some compounds
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Thoughts (cont’d)
▪ Public concern outpacing regulatory developments
▪ Contaminant detection may be viewed as need for treatment
▪ What will CCL look like 10 years from now? 20 years? 50 years? What additional contaminants will be regulated?
▪ An ounce of prevention . . .
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Issues and considerations
• Advanced processes are needed to treat many emerging contaminants
• In some cases, technology decision may be clear cut; in others, not so much
• Advanced processes are expensive – to construct and to operate
• What added benefits do advanced processes offer
• Bench- and/or pilot-scale testing recommended in most cases
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Proposed planning approach
▪ Understand source/watershed – regularly assess risk
▪ Conduct regular source water sampling – be proactive and forward-thinking
▪ Consider “what if?” scenarios
▪ Develop and maintain cyanobacteria contingency plan
▪ Understand operational tools currently available – capabilities and limitations
▪ Incorporate new tools – operational, capital42
Proposed planning approach (cont’d)
▪ Emphasize multiple barrier approach
▪ Allow for future advanced processes (GAC contactors, advanced oxidation, in particular)▪ Hydraulic requirements (to, thru, back)
▪ Space within piping, building
▪ Connections for future piping
▪ Space on site, future building addition
▪ Electrical power, other utilities
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Typical drinking water treatment system
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