Whole Effluent Toxicity (WET)“The Canary in Your Coal Mine”

27th Annual Region VI Pretreatment Workshop

Irving, TXAugust 1-4, 2011

Paul Juarez, 6WQ-PPWhole Effluent Toxicity Coordinator

US Environmental Protection Agencyjuarez.paul@epa.gov

214.665.7247

What exactly is WET?

(Whole Effluent Toxicity / Biomonitoring)

WET, or biomonitoring, is the use of live test organisms to determine the potential toxic impacts of wastewater effluents, stormwater, or other water discharges, on aquatic life in receiving streams and lakes.

Ceriodaphnia dubiaDaphnid - water flea

Pimephales promelas Fathead minnow

Is WET required? If so, why?Is WET required? If so, why?

EPA (and State governments) require wastewater permits to include WET testing to ensure compliance with objectives of the Clean Water Act, federal regulations for NPDES permitting 40 CFR 122.44(d)(1), and State narrative water quality standards to protect aquatic life.

State Water Quality Standard for the Protection of Aquatic Life

After allowing for mixing with receiving water upstream, there shall be no chronic toxicity outside the edge of the defined mixing zone.

Chronic Toxicity — Toxicity which, after long-term exposure, exerts sublethal negative effects, or which is lethal to representative, sensitive organisms.

• A facility must obtain a permit to discharge its wastewater.

• The permit defines what chemicals may be discharged, how much over what time period (mass limits and/or concentration limits).

• Permits also require whole effluent toxicity (WET) testing to determine if the effluent is toxic to aquatic life. If the effluent is toxic, permit limits on WET may be required.

But how can WET benefit my facility?

Failing a WET test usually signals something has gone wrong with the treatment system – either a change in chemicals added, process, OR that the toxicity of your influent has increased for some reason – possibly a new discharger or a change in the effluent discharged by an existing customer. But, while the initial WET test failure may be a negative sign, WET is also a basic tool to find and correct the problem.

Pretreatment WET Testing Pretreatment WET Testing RequirementsRequirements

Pretreatment permits issued by municipalities to their industrial users now include WET monitoring. Such permits usually include quarterly testing with increased frequency following a failure. A failure is defined as a significant lethal or sublethal effect at a critical concentration. That critical concentration is based on the industrial user’s proportion of the POTW’s influent.

Pretreatment – Primary DefensePretreatment – Primary Defense

• Can add additional levels of protection Can add additional levels of protection and influent/effluent toxicity control(s)and influent/effluent toxicity control(s)

• User survey analysis when performing User survey analysis when performing a Toxicity Reduction Evaluation (TRE)a Toxicity Reduction Evaluation (TRE)

• Provides initial points of reference Provides initial points of reference outside the POTWoutside the POTW

• Systematic examination of the user Systematic examination of the user collection systemcollection system

Local LimitsLocal Limits

The goal in developing local limits is to implement pretreatment regulations that are technically and legally defensible. Local limits can include provisions for equitable recovery of costs associated with the toxicity source evaluations and local limits development.

WET ToolsWET Tools

Historical WET test data review – Historical WET test data review – “barely” passing/failing tests?“barely” passing/failing tests?

Internal/external surveys for new Internal/external surveys for new dischargers/chemicals/processesdischargers/chemicals/processes

Toxicity data review for new/altered Toxicity data review for new/altered treatment compounds or supplierstreatment compounds or suppliers

Upstream Sampling (no advance Upstream Sampling (no advance notice – toxicity may temporarily notice – toxicity may temporarily disappear)disappear)

Streamlined WET tests (cheap, use to Streamlined WET tests (cheap, use to find toxic samples for toxicant find toxic samples for toxicant analysis)analysis)

Facility-Specific Information

• Industrial waste surveys• Industrial user self-monitoring

reports• Industrial user operational

schedules and flow patterns• Waste hauler monitoring and

manifests• Hazardous waste inventories

System System Inspections/SamplingInspections/Sampling

• System inspectionsSystem inspections• Microtox, ELISAMicrotox, ELISA• Streamlined WET testsStreamlined WET tests• Onsite facility Onsite facility

inspectionsinspections• Advance notice to Advance notice to

users?users?

Detective WorkDetective Work

• What else is going on? Are there records What else is going on? Are there records that correlate WWTP / SIU activities and that correlate WWTP / SIU activities and reduced/increased toxicity?reduced/increased toxicity?

• Develop chemical usage profile for SIUsDevelop chemical usage profile for SIUs• Batch or seasonal processes/chemicals?Batch or seasonal processes/chemicals?• Communicate Communicate

Communicate Communicate CommunicateCommunicate

Uncovered storage orprocess areas

Cameras and “Sniffers”

TRE - TTRE - Toxicity Reduction oxicity Reduction EvaluationEvaluation

A study to identify causes and controls for effluent toxicity – begin by gathering information:

• Historical effluent toxicity data• Treatment plant design capabilities• Operation and maintenance practices• Industrial user permits• Pretreatment inspection reports• Monitoring and compliance reports• RECENT CHANGES, UPSETS

Toxicity Reduction Evaluations Toxicity Reduction Evaluations (TREs)(TREs)

• Resolution depends on toxicity magnitude / duration

• Many facilities have worked aggressively and resolved both lethal and sub-lethal toxicity issues

• Unresolved toxicity usually related to inexperience or sloppy work, sampling or lab

• Success is usually a result of good communications and coordinated efforts between the TRE/WET testing consultant, the permittee and the permitting authority

Commonly Found Toxicants:

Chlorine Ammonia Copper Zinc Nickel Tributyltin Total Dissolved Solids (TDS) (Potassium, Bicarbonate, Calcium) Organophosphate Pesticides

(Diazinon, OXO-Diazinon, Chlorpyrifos)

Pathogenic Interference – Not acceptable for POTWs, which are designed to treat for pathogens.

POTW was in violation of its WET limits >>> TRE

In-house processes were reviewed and corrected, and toxicity was reduced but not eliminated

A toxicant identification evaluation (TIE) revealed high levels of pesticides in the effluent and a pretreatment user review showed treatment inefficiencies at a pesticide manufacturer.

The pesticide facility eventually found it had 2 problems:

Pretreatment TRE Pretreatment TRE ExampleExample

Example (Cont.)Example (Cont.)

1) Dye studies showed the settling pond with 4-7 days retention actually had only 1.5 hours retention

2) Storage barrel rinse water was dumped directly to the retention pond. Pesticide slugs were passed from the settling pond directly to the POTW influent

The TRE established two control strategies:

1) Dredge the pond and install a baffle system to increase the retention time

2) Reroute storage barrel rinse water to treatment cycle

TRE / TIETRE / TIE A TRE is a A TRE is a studystudy to determine the source(s) of toxicity to determine the source(s) of toxicity

in an effluent and identify potential treatment options.in an effluent and identify potential treatment options. A TIE is a set of effluent manipulations designed to A TIE is a set of effluent manipulations designed to

identify pollutants. EPA identify pollutants. EPA recommendsrecommends TIEs as part of a TIEs as part of a TRE. TRE.

The presence of toxicity in samples is a cornerstone of The presence of toxicity in samples is a cornerstone of TRE success – this means increased testing frequency TRE success – this means increased testing frequency and obtaining adequate amount of sample for WET and and obtaining adequate amount of sample for WET and chemical testing.chemical testing.

TRE duration should be sufficient to perform the work.TRE duration should be sufficient to perform the work. Concerned parties should meet at start and end of the Concerned parties should meet at start and end of the

TRE.TRE. Most R6 TREs have been successful. Inconclusive TREs Most R6 TREs have been successful. Inconclusive TREs

occur – but even those have eventually been resolved.occur – but even those have eventually been resolved.

Planning is importantPlanning is important

WET Test Data Review

Your permit explains your various WET reporting codes. A good WET test lab report should contain a page showing the results for each reporting code as well, plus the bench sheets raw data and the statistical analysis, for review by you or the permit authority.

Example Permit, Part II, WET language, Reporting Section (Section 3 or 4)

ii. Ceriodaphnia dubia

1. If the NOEC for survival is less than the critical dilution, enter a ‘1’; otherwise, enter a ‘0’ for Parameter No. TLP3B1. Report the NOEC value for survival, Parameter No. TOP3B2. Report the LOEC value for survival, Parameter No. TXP3B3. Report the NOEC value for reproduction, Parameter No. TPP3B4. Report the LOEC value for reproduction, Parameter No. TYP3B5. If the No Observed Effect Concentration (NOEC) for reproduction is

less than the critical dilution, enter a ‘1’; otherwise, enter a ‘0’ for Parameter No. TGP3B1. Report the higher (critical dilution or control) Coefficient of Variation, Parameter No. TQP3B

Your lab’s WETreport shouldalways include afull statisticalanalysis of yourWET data!

Your lab’s WET reportshould also alwaysinclude theactual raw data sheets.

Does your lab providea full statistical analysisand the raw data sheetsfor each test?

Permitting authoritieswill be looking for theseany time they arereviewing your files.

Example of Graphed Chronic Test DataExample of Graphed Chronic Test Data% Effluent

Concentration

# of young(Total = 33)

Percent Effluent (log scale)

30

25

20

15

10

5

010 100

NOEC

Ad

just

ed

Nu

mb

er o

f Y

ou

ng

100%

33

50%

33

25%

33

12.5%

33

6.25%

13

0%

0

35

LOEC

Note: As theconcentrationof effluentincreases, reproductiondecreases.

Now let’s look at some of the basic informationyou should be able to digout of that 30-page WETtest report…

Note CVs in Performance v Dilution Water v Low-Flow Concentrations: lower CVs = lower variability

All effluent concentrations passed, 1 organism died (56% effluent)

IC25 analysis may or may not agree withNOEC analysis. Permits in Region 6 Statesstipulate NOEC as the test endpoint.

Example of a failedtest. While the doseresponse isn’t pretty,it is obvious thatsomething is goingon with this effluent.

Example of afalse positive.The data herewas very tight.As a result, theeffluent failed but it should not have.

This situation was corrected by increasing to 5 replicates.

25% effluentconcentration‘passed’ withonly 50%survival in 15%concentration.

Example of afalse negative,rarely reported.

Corrected by revising the concentration series.

Because we all want our water to be ‘clean’…

Thank you for your attention Thank you for your attention today. Please feel free to ask today. Please feel free to ask any questions or contact me at:any questions or contact me at:

juarez.paul@epa.govjuarez.paul@epa.gov

(214) 665-7247(214) 665-7247