Transcript Will CWA 316b Regulations End Chemical Cooling

Will CWA 316b Regulations End Chemical
Cooling Water Treatment Programs?
Mary Wolter Glass
President, Mexel USA, LLC
February 17, 2015
No, but it will not be the same!
• Imposed opportunity to improve cooling water
system performance
• Take control of the regulatory planning process to
enhance operational and financial goals
• Challenge: craft unique solutions for the business
that will succeed with regulators
Factors Permit Writers Will Consider
• Reliability and cost of electric service
• Technical feasibility and financial costs and benefits
• Land availability for BTA and ongoing operations
• Compatibility of entrainment BTA with impingement
technology adopted
• Remaining useful life of the plant
Factors Permit Writers Will Consider
• Social costs and benefits of alternative entrainment
technologies
• Water sources and alternatives available
• Numbers & types of organisms
• Potential to increase air and other pollution
Untreated Inlet Water Box - Hydroids
Treated Inlet Water Box
Macro Biofouling Prevention
“Before”
“After”
7
Quagga Mussel Damage
Identifying 316b Options
• Define minimal performance requirements for plant
– operating schedule, availability, and capital and
maintenance costs
• Evaluate options for:
– Ease and cost of compliance
– Compatibility of combined options
– Potential unintended impacts of compliance, e.g.• Increased fouling due to lower velocities
• Impingement devices that increase entrainment
mortality and vice versa
Implementation
•
BTA impingement technology options well-defined
•
Entrainment BTA is site-specific and more complicated
•
Impingement implementation can be delayed to allow
planning for entrainment
•
“Unknowns” still create risk for technology selections Endangered Species Act, Federal Agency reviews,
litigation
316(b) & Chemicals
•
•
•
Chemical treatment necessary for plant performance
Mortality from impingement and entrainment linked
– Mechanical, thermal and chemical factors
– Intake and water circuit design affects fouling
Multiple BTA solutions –
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–
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Carefully designed mechanical & chemical programs
Adjustments to operations, scheduling
Collaboration of environmental and operations staff to
balance
– Optimal environmental performance
– Operational/financial realities
Chemical Program Objectives
• Evaluate purpose of current program
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–
–
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What problems lead to current choices?
Do problems persist? New problems?
Is the program still achieving desired results?
Future viability of program with regulators?
• Examine plant design and fouling issues
– Intake and water circuit characteristics
– Plant operating conditions, schedules
– Biological fouling – species, operating conditions, ambient
environmental conditions
– Corrosion, scaling, mud, etc.
Current Program Review
• Chemical program components
– Inventory all chemicals and the purpose – direct and indirect
– Document toxicity of each in detail
• Certified laboratory studies
• Field studies
• Related these to critical species at site
• Non-chemical devices and practices
– Screens (travelling & fixed), filters, nets, etc.
– Operating schedules and constraints
• Effects on impingement and entrainment
• Constraints on critical production schedules
Shaping the Best Program
• Detailed information on toxicity and other risks from
manufacturers for in-house environmental review
– MSDS and product label
– Extensive lab and field research data, results
• Program should minimize number of chemicals based
– Efficacy vs. adverse impacts
– Safer alternatives
• Field and laboratory test results from existing and new studies
– Species-specific studies – bench-scale, unit trials, laboratory, bench
scale
– Sensitivity studies for critical species
– Whole Effluent Toxicity Tests (WET tests)
– Local ecosystem and biodiversity studies
Technology Combinations
• Combine technologies with chemicals for BTA
– Acoustic or other fish deterrent systems divert target species
before exposure to chemicals occurs
– Passive and traveling screens,
• Mesh size and operating speed factors
• Entrainment mortality can vary widely
• Lower velocities may aggravate existing fouling problems
– Increased blend of reclaimed water and other water sources to
reduce mortality losses - increases chemical requirements and
operating complexities
• Combine chemicals with operations and maintenance
practices
– Cleaning and operating practices to reduce chemical
requirements
Technology Combinations
Condenser
Backpressure
Di-oxide chlorine treatment +
mechanical ball cleaning
- 1.53%
- 1.5%
- 1,48%
- 1.25% (.23% improvement)
Ref = 0.00
MEXEL 432 treatment alone
- 0.8% (.73% improvement)
04 November
- 0.5%
25 September
- 1.0%
6 weeks
Chlorine & Ball System vs.Mexel 432/0
Making Your Case
•
Factors to enhance regulatory acceptability
– Lower chemical toxicity
• reduces direct lethality
• helps reduce the effects on organisms from other thermal
and mechanical stressors
– Shorter dosing pattern reduces total daily exposures
– Reduced number of chemicals required
– Chemicals that do not require detoxification or remediation
for discharge
•
Fully document the case for chemicals as a necessary part of BTA
www.mexelusa.com
17
Relative Toxicity Matters
• Freshwater Crustaceans
– Mexel 432/0
• Daphnia magna - Effect Concentration (EC)50 (48 hour): 554 ppb
• Daphnia magna - No Observed Effect Concentration (NOEC) (21 day) 200 ppb
– NaClO
• invertebrate: Lethal Concentration (LC)50 (24 hour) 5 ppb
• Seawater fish
– Mexel
• Scophthalmus maximus (juvenile) - LC50 (96hour): 3,700 ppb
– NaClO
• Scophthalmus maximus (juvenile) - LC50 (96 hour): 32 – 90 ppb
Source: Mexel Industries, SAS 2013
Biofilm Control
Untreated
Treated
Untreated
Treated
Untreated
Treated
Condensers After 5 Months
Unit 5 – Untreated
Unit 6 – Treated with Mexel 432/0
New Water Treatment Options the Mexel 432/0 Example
• Based on filming amine technology, not lethal slug or
continuous treatments
– Molecular layer on the inside surfaces
– Dispersant/detergent with mild biocide
– Prevents and remediates fouling over time
– Protects surfaces and equipment to avoid problems
– Replaces multiple chemicals for corrosion, scaling, mud
• Application in once-through and cooling tower systems
– Emulsion injected at intake for 30 minutes per day
– Typical dosing rate of 4 to 5 ppm
• Works in fresh, saline, and reclaimed water systems
Mexel Filming Process
to Prevent Fouling
Mexel® 432/0
Mexel® 432/0
Condenser
tube
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Biofilm, etc.
Removal
process
Full thermal transfer
re-established
In Conclusion
• Opportunities to improve operational and
financial performance along with environmental
objectives
• Factors beyond environmental will be considered
in determining BTA
• Numerous good chemical options available
• Best selections for BTA will balance plant public
service responsibilities with the environment
www.mexelusa.com
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MUSA
316(b)