Know your Solutions!
For many years, treatment of baghouse dust “in-line” has been used to keep overhead costs to a minimum and to avoid the generation of hazardous waste. Although most people only look at the final results of the Toxicity Characteristic Leaching Procedure (TCLP), there are several important things to know about the actual test procedure.
All solutions are not created equal…
The key to understanding the TCLP (EPA SW846 Method 1311) is being aware of which leaching solution is being used. There is a preliminary evaluation in the TCLP that is used to establish the initial pH of the waste which determines whether to continue with Solution 1 (a dilute acid with a pH of 4.93) or Solution 2 (a strong acid with a pH of 2.88). If the initial pH of the waste is less than 5, then Solution 1 is used. If the pH of the waste is above 5 at the end of the “pre-test” then Solution 2 is used. Since it is a stronger acid, higher concentrations of metals will leach out using Solution 2.
Earlier this year, an EnviroBlend client noticed inconsistent TCLP results and contacted an EnviroBlend representative. After questioning, the laboratory agreed that they were not consistently utilizing the correct TCLP preliminary procedure. This, of course, can lead to disposing of non-hazardous waste as hazardous or hazardous waste as non-hazardous. Both situations are risky and expensive and EnviroBlend personnel have seen this too often. It is important to make sure the laboratories are running the pre-test for each sample.
To learn more about this topic contact EnviroBlend at 800-227-4287 or visit the U.S. Environmental Protection Agency website to read the full SW-846 Test Method 1311: Toxicity Characteristic Leaching Procedure.