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WHOLE EFFLUENT TOXICITY. What is whole effluent toxicity? What is whole effluent toxicity? - testing a wastewater discharge with aquatic organisms to.

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Presentation on theme: "WHOLE EFFLUENT TOXICITY. What is whole effluent toxicity? What is whole effluent toxicity? - testing a wastewater discharge with aquatic organisms to."— Presentation transcript:

1 WHOLE EFFLUENT TOXICITY

2 What is 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 Understanding WET 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

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

5 WET Freshwater Chronic Test Species Invertebrates: –Ceriodaphnia dubia Fish –Pimephales promelas - Fathead Minnow Algae –Selenastrum capricornutum

6 Test Data i. Typical dose response where mortality increases as the concentration of effluent in the mixture increases. ii. LC 50 would be somewhere between 25% effluent and 50% effluent. 0% Mortality0% mortality20 % Mortality40% Mortality 80% Mortality100% Mortality 6.25 % Effluent Control 12.5 % Effluent 25.0% Effluent 50.0% Effluent 100.0% Effluent New Jersey Saline Acute Test Species

7 Test 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

8 Grab vs. Composite Grab samples offer snap shot of effluent Grab samples offer snap shot of effluent Composite samples offer average view of effluent Composite samples offer average view of effluent NJDEP requires sampling based on discharge type NJDEP requires sampling based on discharge type i.Continuous discharge – 24 hour composite sample ii.Intermittent discharge – grab or composite each day that is representative of discharge

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. 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 not to be used after they have been held for 72 hours. Samples are to be chilled during or immediately upon collection to 4 o C. Samples are to be chilled during or immediately upon collection to 4 o C.

10 WET Monitoring a fathead minnow test Opossum Shrimp Pimephales promelas

11 WET Procedures

12 Pimephales 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.

13 Tests Results in Canada

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