WHOLE EFFLUENT TOXICITY

WHOLE EFFLUENT TOXICITYWHOLE EFFLUENT TOXICITY

What is whole effluent toxicity?What is whole effluent toxicity?

- testing a wastewater discharge testing a wastewater discharge

with aquatic organisms to assess with aquatic organisms to assess

the discharge's toxicitythe discharge's toxicity

- WET is a standardized protocol WET is a standardized protocol

(ex the Standard Methods(ex the Standard Methods

Understanding WETUnderstanding WET - An effluent may be complying with all the - An effluent may be complying with all the

individual parameter limits but does it individual parameter limits but does it guarantee that it will not cause any guarantee that it will not cause any detrimental effects of the aquatic detrimental effects of the aquatic organisms?organisms?

- WET attempts to answer this question WET attempts to answer this question and quantify the effectsand quantify the effects

- WET is an aquatic toxicity/bioassay test WET is an aquatic toxicity/bioassay test

WHOLE EFFLUENT TOXICITYWHOLE EFFLUENT TOXICITY

WHOLE EFFLUENT TOXICITYWHOLE EFFLUENT TOXICITY

Understanding WETUnderstanding WET

- Acute test (24 to 96 hrs)Acute test (24 to 96 hrs)

- Chronic test (~ 7 days)Chronic test (~ 7 days)

WHOLE EFFLUENT TOXICITYWHOLE EFFLUENT TOXICITY

WET Freshwater Chronic Test SpeciesWET Freshwater Chronic Test Species

InvertebratesInvertebrates: : – Ceriodaphnia dubiaCeriodaphnia dubia

FishFish– Pimephales promelasPimephales promelas - Fathead Minnow - Fathead Minnow

AlgaeAlgae– Selenastrum capricornutumSelenastrum capricornutum

Test DataTest Datai.i. Typical dose response where Typical dose response where mortality increases mortality increases

as the as the concentration of effluent in the mixture concentration of effluent in the mixture

increasesincreases..

ii.ii. LCLC5050 would be somewhere between 25% effluent would be somewhere between 25% effluent

and 50% effluent.and 50% effluent.

0% Mortality 0% mortality 20 % Mortality 40% Mortality 80% Mortality 100% Mortality

6.25 % EffluentControl

12.5 % Effluent

25.0% Effluent

50.0% Effluent

100.0% Effluent

New Jersey Saline Acute Test Species

Test ResultTest Result

New Jersey Saline Acute Test Species

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”

Grab vs. CompositeGrab vs. Composite Grab samples offer “Grab samples offer “snap shotsnap shot” of effluent” of effluent

Composite samples offer “Composite samples offer “average viewaverage view” ” of effluentof effluent

NJDEP requires sampling based on NJDEP requires sampling based on discharge typedischarge type

i.i. Continuous discharge Continuous discharge – 24 hour composite – 24 hour composite

samplesample

ii.ii. Intermittent discharge Intermittent discharge – grab or composite – grab or composite

each day that is representative of dischargeeach day that is representative of discharge

Grab vs. CompositeGrab vs. Composite Type of sample and frequency of Type of sample and frequency of

collection is dependent upon the use collection is dependent upon the use of the data and the discharge the of the data and the discharge the test is intended to represent.test is intended to represent.

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

Samples are to be chilled during or Samples are to be chilled during or immediately upon collection to 4immediately upon collection to 4ooC.C.

WETWET Monitoring a fathead minnow testMonitoring a fathead minnow test

Opossum Shrimp

Pimephales promelas

WET ProceduresWET Procedures

Pimephales promelasPimephales promelas

Photo by Karen McCabe from Animal Soup

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

Tests Results in CanadaTests Results in Canada

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