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WHOLE EFFLUENT TOXICITY. WHOLE EFFLUENT TOXICITY. What is whole effluent toxicity? testing a wastewater discharge with aquatic organisms to assess the discharge's toxicity WET is a standardized protocol (ex the Standard Methods. WHOLE EFFLUENT TOXICITY. Understanding WET

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WHOLE EFFLUENT TOXICITY

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WHOLE EFFLUENT TOXICITY


WHOLE EFFLUENT TOXICITY

What is whole effluent toxicity?

  • testing a wastewater discharge with aquatic organisms to assess the discharge's toxicity

  • WET is a standardized protocol (ex the Standard Methods


WHOLE EFFLUENT TOXICITY

Understanding WET

- An effluent may be complying with all the individual parameter limits but does it guarantee that it will not cause any detrimental effects of the aquatic organisms?

  • WET attempts to answer this question and quantify the effects

  • WET is an aquatic toxicity/bioassay test


WHOLE EFFLUENT TOXICITY

WHOLE EFFLUENT TOXICITY

Understanding WET

  • Acute test (24 to 96 hrs)

  • Chronic test (~ 7 days)


WET Freshwater Chronic Test Species

Invertebrates:

  • Ceriodaphniadubia

    Fish

  • Pimephalespromelas- Fathead Minnow

    Algae

  • Selenastrumcapricornutum


Test Data

  • Typical dose response where mortality increases as the concentration of effluent in the mixture increases.

  • LC50 would be somewhere between 25% effluent and 50% effluent.

6.25 % Effluent

12.5 % Effluent

25.0% Effluent

50.0% Effluent

100.0% Effluent

Control

0% Mortality

0% mortality

20 % Mortality

40% Mortality

80% Mortality

100% Mortality

New Jersey Saline Acute Test Species


Test Result

Calculated point estimate or a Pass fail test where a concentration, usually that which is considered a critical concentration of effluent in the receiving water or ambient toxicity test measured against a control

Examples of Pass/Fail Acute test

Instream waste concentration (IWC) = 75% statistical evaluation using a student-t test compares mortality rates of ambient or IWC sample against a control.

Is there a “significant statistical difference between the two results”

New Jersey Saline Acute Test Species


Grab vs. Composite

  • Grab samples offer “snap shot” of effluent

  • Composite samples offer “average view” of effluent

  • NJDEP requires sampling based on discharge type

    • Continuous discharge – 24 hour composite sample

    • Intermittent discharge – grab or composite each day that is representative of discharge


Grab vs. Composite

  • Type of sample and frequency of collection is dependent upon the use of the data and the discharge the test is intended to represent.

  • Samples are not to be used after they have been held for 72 hours.

  • Samples are to be chilled during or immediately upon collection to 4oC.


WETMonitoring a fathead minnow test

Opossum Shrimp

Pimephales promelas


WET Procedures


Pimephalespromelas

Adults are small fish typically 43 mm to 102 mm, and averaging about 50 mm, in total length.

Photo by Karen McCabe from Animal Soup


Tests Results in Canada

http://www.ec.gc.ca/


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