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L16 COM MERCIAL TESTING & ENGINEERING CO. DISCUSSION In October of 2002 the quarterly, routine Whole Effluent Toxicity test failed for Daphnia magna. Two, subsequent accelerated tests also failed, thereby establishing a "pattern of toxicity". Upon reviewing effluent chemical data from both the routine and accelerated tests and comparing it with current effluent chemical data, CT&E decided to run a more simplified series of tests (PTI) geared specifically towards confirming TDS and/or cationic metals toxicity. Several of the tests performed in this Preliminary Toxicity Identification removed or reduced toxicity. The tests that removed toxicity include the acid/base ion exchange resin test and the pH 3.0 adjustment/aeration test. The tests that strongly reduced toxicity include the pH 3.0 adjustment/filtration test, no pH adjustment/filtration test, post C~a SPE column test, and the EDTA addition test. The tests that did not remove or slightly reduce toxicity include the pH 10 adjustment/aeration test, no pH adjustment/aeration test, and pH 10 adjustment/filtration test. Based on the results of this PTI, the following observations were made that could indicate that cationic metals or cationic surfactants may be the source of toxicity: • The EDTA addition test moderately reduced the toxicity (USEPA 1992). EDTA has a strong affinity for and complexes with cationic metals so that they are not bioavailable. The post Cis SPE column test significantly reduced the toxicity_ This is an indication of cationic surfactant toxicity. Also, combined with the reduced toxicity in the EDTA addition test, is an indication of cationic metals toxicity (USEPA 1992). The function of the post Cis SPE column test is to remove cationic metals and reduce toxicity due to inorganic constituents. • The toxicity is reduced in the filtration tests, especially when the pH adjustment (3 or 10) and filtration are combined (USEPA 1992). This is an indication of both cationic metals and cationic surfactant toxicity. • The toxicity reduction is similar in both the post Cis SPE column test and filtration tests (USEPA 1992). This is an indication of cationic surfactant toxicity. • The acid base ion exchange resin removed the toxicity. This is an indication that both toxic anions and cations are removed. The resulting conductance was reduced. (USEPA 1993). • The pH 3 adjustment/aeration test removed the toxicity. This is an indication that metal hydroxide complexes disassociated, allowing the cationic species to become metal oxides in air sparged water. To support this thought pattern; the pH 10 adjustment/aeration test fared no better than the baseline degradation test. This indicates that metal hydroxide complexes