“WETing Your Appetite”

Bruce Rabe

ERM

Agenda

• What is WET Testing

• Historical and statutory background of the WET program

• State regulatory requirements

• Test Methodology

• TRE/TIE

• “Value Added” Practices

• Emerging Issues

What is WET Testing?

• A form of biological monitoring used to determine (predict) whether a wastewater discharge will have toxic effects on the organisms in the receiving water

• WET (proactive) vs Ecological Survey (reactive)

• Indicator Organism

Historical Prospective

• Over 2000 years ago, Aristotle studied freshwater vs saltwater effects

• 1800‟s - toxicity tests on chemical and drugs

• early 1900‟s - effects of toxic materials on organisms besides humans

• 1950‟s - reactive to proactive (effluent toxicity tests)

Early Use of Toxicity Testing in The EPA WET Program

• 1974, Region 4 conducted on-site acute tests

• 1976, industrial facilities conducted acute tests

• 1983, began use of short-term chronic testing

• 1983, WET predictor of receiving water toxicity

• 1984, EPA recommended use of WET limits

• 1985, EPA TSD for toxics control

• 1991, EPA revised TSD for toxics control

• 1995, EPA promulgated test methods (11/15/95)

• 1999, EPA clarified method language (3/5/99)

Statutory Basis for WET Regulations

• Section 101(2), Federal Clean Water Act:– „…discharge of toxic chemicals in toxic amounts shall

be prohibited‟

• R1057(1), Michigan Natural Resources and Environmental Protection Act:– „Toxics shall not be present at levels which are or may

become injurious…‟

• R1057(6):

– „Whole-effluent toxicity requirements may be used

to ensure… requirements are met‟

Statutory Basis for WET Regulations

• R1219: Whole Effluent Toxicity

– Interprets 1057(6) narrative criterion:

– Allows 1.0 TUa at point of discharge

– Allows 1.0 TUc after mixing

WET Limit Development

• Acute Requirement if >80:1 Dilution

• Chronic Requirement if <80:1 Dilution

– annual average design flow (municipalities)

– authorized flow (other facilities)

– lowest monthly 95% exceedance flow (river)

– up to 10x mix for lake

WET Limit Calculation

• Acute WET Limit = 1.0 (no dilution)

• Chronic WET Limit

– Flowing water

• Qe+Qr/Qe x Allowable TUc

– Qe = Effluent design/authorized flow

– Qr = 1/4 of lowest monthly receiving water 95% exceedance flow

– Lakes

• Mix allocated (1X - 10X) x Allowable TUc

Conditions for Applying WET Limit

• Limit when Reasonable Potential to exceed narrative standard exists:

Mean measured TU>Preliminary Limit (PEL)

• Exception: WET compliance can be assured by chemical-specific limit in some cases

Typical WET Permit Sequence

• Monitor program– Generate database

• Interim limit– schedule of compliance (3 years)

– no numerical limit

– Toxicity Reduction Evaluation (TRE)

– quarterly WET monitoring

• Final limit– monthly monitoring

MDNRE Test Requirement

• Acute Toxicity Tests

– 48 hour definitive static non-renewal with (Daphnia magna, Daphnia pulex or Ceriodaphnia dubia)

– 96 hour definitive static renewal with fathead minnow (Pimephales promelas)

MDNRE Test Requirement

• Chronic Toxicity Tests

– Daphnid, Ceriodaphnia dubia, survival and reproduction test (method 1002.0)

– Fathead minnow, Pimephales promelas, larval survival and growth test (method 1000.0)

Summary of Test Conditions

• Each method has required test conditions:

– sampling and holding time requirements

– test type and duration

– species selection, age, feeding

– temperature, light, dissolved oxygen

– test chamber size, volume and replication

– dilution water

– dilution series

– test acceptability criteria

Test Acceptability Criteria

• Acute Toxicity Tests

– Survival = 90%

• Chronic Toxicity Tests

– Survival = 90%

– Reproduction = 15 young/female

– Growth = 0.25 mg

• Acute/Chronic Toxicity Tests

– Dose response

Accuracy and Precision

• Accuracy

• Precision (Standard Reference Toxicant)– intralaboratory (SRT Control Chart)

– interlaboratory (DMR-QA Program)

• Precision estimates given as coefficient of variation (CV)

• Percent Minimum Significant Difference (MSDp)

Quality Assurance and Quality Control

• Elements of a QA/QC Program

– Appoint a QA/QC Officer

– Written QA Plan with DQOs

– Standard Operating Procedures (SOPs)

– Approved EPA/MDEQ methods for WET

– Record keeping

– Qualified staff

– Suitable space and equipment

– Dilution/culture water

Data Reduction/Reporting Requirements

Data Information Test Result

Acute

Survival LC50 TUa Pass/Fail

Chronic

Survival NOEC/LOEC

Sub-Lethal NOEC/LOEC

ChV TUc Pass/Fail

Data Reduction/Reporting Requirements

• Acute Test Data

– TUa = 100/LC50

• Permit Limit of 1.0 TUa requires <50 percent mortality in 100 percent effluent

– TUa <1.0 (LC50 >100 percent)

• If mortality is 0 - 10 percent, TUa reported as 0

• If mortality is 11 - 49 percent, TUa reported as:

– 0.02 x percent mortality

– Example: TUa = 0.02 x 25% mortality = 0.5 TUa

Data Reduction/Reporting Requirements

• Chronic Test Data– Control 25.0 young/female

– 6.25% 24.3 young/female

– 12.5% 23.9 young/female

– 25% 21.0 young/female

– 50% 21.6 young/female NOEC

– 100% 9.8 young/female LOEC

Chronic Value/MATC = NOEC x LOEC = 50 x 100 = 70.7

TUc = 100/ChV = 100/70.7 = 1.4

TRE

TRE Approach

• What is a TRE and when is it used?

• Logical starting place is a thorough information gathering phase

Municipal TRE Approach

• Accelerated WET testing

• NPDES permit evaluation

– what are the toxicants identified in the permitting process?

• Treatment system design criteria, flow diagrams, descriptions of treatment process

• Is the system operating up to design specifications, e.g. removal efficiencies?

Municipal TRE Approach

• Trend Analysis

– Sources/relative contributions of wastewater

– Influent and effluent flow/operational data

– How do flows relate to observed toxicity

– Short or long term variation in toxicity related to flow, rainfall, industrial user operating schedules, seasons

Municipal TRE Approach

• Process control and operational data and histories

• In-plant chemical usage (e.g., polymers, coagulants, chlorine)

• Treatment upset histories and reports

• Pretreatment information

Municipal TRE Approach

• Industrial waste surveys

• Industrial user self-monitoring reports

• Industrial user operational schedules and flow patterns

• Waste hauler monitoring and manifests

• Hazardous waste inventories

Different Municipal Approaches• RTAs

– bench simulations of treatment process (activated sludge) to determine toxicity pass-through

• Pretreatment toxicity limits

– treatability options

• Public education

– environmental and cost considerations of household waste disposal practices and hazardous waste collection activities

Industrial TRE Approach

• Process Engineering Analysis

– Material Inventory

– Examination of Relevant Literature

– Comparison of Effluent with Raw Material Inventory

• Toxics Control Evaluation

– Inplant Controls

– Resource Recovery

– Good Housekeeping Measures

– Alternative Waste Management Practices

Toxicity Identification Evaluation (TIE)

• Initial Toxicity Assessment

– Effluent Toxic (Acute/Chronic)

– Consistent Toxicity

– Species Sensitivities Consistent

– Toxicity Persistent

Toxicity Identification Evaluation (TIE)

• Phase I - Characterization

– Toxicant Grouping (metal, organic, volatile, pH dependent, etc.)

• Phase II - Identification

– Specific compound(s)

• Phase III - Confirmation

– Weight of Evidence Testing

Partial List of Causative Agents• Zinc, Nickel, Copper

• Ammonia

• Surfactants

• Chlorine

• Salinity (TDS)

• Diazinon, Chlorofenvinphos, Dichlorvos,

• Polymers

• Biocides, etc...

Ammonia Is Suspect Toxicant When:

• Toxicity is greater to fathead minnows than Ceriodaphnia

• Toxicity reduced with low pH‟s

• Post-zeolite column effluent is non-toxic and ammonia levels are reduced

• Large surface/volume air-stripping reduces toxicity

• Total ammonia measured is > 5 mg/L

TDS Is Suspect Toxicant When:

• None of the conventional characterization procedures reduce toxicity

• Conductivity measured is > 2,000 umhos/cm

• Salinity Toxicity Relationship (STR)

• Mock Effluent Evaluation

• Daphnia magna Chronic Test

“Value Added” Practices

• Monitor Your System

• Use Your Allowed Dilution

• Statistical Significance Rate (alpha)

• Testing Frequency Reductions

Emerging Issues

• Pathogen/Artifact Toxicity

• Selenium

• Endocrine Disrupting Chemicals (EDC)

• Nanoparticles

Method Documents

• Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms - EPA-821-R-02-012

• Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms - EPA-821-R-02-013

• Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms - EPA-821-R-02-014

• Toxicity Reduction Evaluation Guidance for Municipal Wastewater Treatment Plants -EPA/833B-99/002

• Generalized Methodology for Conducting Industrial Toxicity Reduction Evaluations (TREs) – EPA/600/2-88/070

• Phase I Toxicity Characterization Procedures - EPA/600/6-91/003

• Phase I Characterization of Chronically Toxic Effluents – EPA/600/6-91/005F

• Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity – EPA/600/R-92/080

• Phase III Toxicity Confirmation Procedures for Samples Exhibiting Acute and Chronic Toxicity – EPA/600/R-92/081