Will CWA 316b Regulations End Chemical

Cooling Water Treatment Programs?

Mary Wolter GlassPresident, 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

7

“Before”

“After”

Macro Biofouling Prevention

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 – – 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– 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

• 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

Technology Combinations

25 S

epte

mbe

r

04 N

ovem

ber

- 1.5%

- 1.0%

- 0.5%

Ref = 0.00

- 1.25% (.23% improvement)

- 0.8% (.73% improvement)

- 1,48%

- 1.53%

6 weeks

CondenserBackpressure Di-oxide chlorine treatment +

mechanical ball cleaning

MEXEL 432 treatment alone

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

17www.mexelusa.com

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 6 – Treated with Mexel 432/0

Unit 5 – Untreated

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

22

Mexel Filming Process to Prevent Fouling

Condenser tube

Biofilm, etc.

Mexel® 432/0

Mexel® 432/0

Full thermal transfer re-established

Removal process

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

316(b)MUSA www.mexelusa.comFollow us on Twitter: www.twitter.com/mexelusaFollow us on LinkedIn: www.linkedin.com/company/mexel-usa