1. WHOLE EFFLUENT TOXICITY

2. 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

3. 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

4. WHOLE EFFLUENT TOXICITY
Understanding WET
Acute test (24 to 96 hrs)
Chronic test (~ 7 days)

5. WET Freshwater Chronic Test Species
Invertebrates:
Ceriodaphnia dubia
Fish
Pimephales promelas - Fathead Minnow
Algae
Selenastrum capricornutum
Though algae are contained in the program, they are not used.

6. 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.
calculated point estimate or a
Pass fail test where a concentration, usually that which is considered a critical concentration of effluent in the recieving water or
ambient toxicity test measured against a control
Examples of Pass/Fail Acute test
Instream waste concentration equals 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”
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

7. Test Result Examples of Pass/Fail Acute test
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”
calculated point estimate or a
Pass fail test where a concentration, usually that which is considered a critical concentration of effluent in the recieving water or
ambient toxicity test measured against a control
Examples of Pass/Fail Acute test
Instream waste concentration equals 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

8. 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
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.

9. 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.
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.

10. WET Monitoring a fathead minnow test
Opossum Shrimp
Pimephales promelas

11. WET Procedures

12. Pimephales promelas
Adults are small fish typically 43 mm to 102 mm, and aceraging about 50 mm, in total length.
Widely distributed in North America. In muddy brooks, streams creeks, ponds and small lakes, is uncommon or absent in streams of moderate and high gradients and in most of the larger and deeper impoundments, and is tolerant of high temperature and turbidity, and low oxygen concentrations.
bait fish
breeding males develop a conspicuous, narrow, elongated, gray, fleshy pad of spongy tubercles on the back, anterior to the dorsal fin, and two or three rows of strong nuptial tubercles across the snout.
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

13. Tests Results in Canada