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<br /> <br />Figure 5: 1,4-Dioxane UV Reactor Influent and Effluent Concentrations <br /> <br />Run 1 was a control test that was not expected to provide any treatment of 1,4-dioxane. This was <br />conducted to demonstrate that the system operation and sample collection, handling and analytical <br />procedures did not produce anomalous results. As Table 2 and Figure 5 show, the influent and effluent <br />1,4-dioxane concentrations for run 1 were almost identical. Run 2 was performed to demonstrate that <br />significant 1,4-dioxane destruction does not occur in the absence of H 2 O 2 . The results demonstrate <br />that only 0.08-log destruction of 1,4-dioxane occurred and it is possible that a trace of H 2 O 2 may have <br />been present even though the H 2 O 2 pump was off. For all the other test runs in which both UV energy <br />and H 2 O 2 were present the 1,4-dioxane reductions were substantial. <br />Figure 6 presents the log reduction of 1,4-dioxane that was measured for each of the 11 test runs. Log <br />reduction is calculated by taking the logarithm of the influent 1,4-dioxane concentration divided by the <br />effluent 1,4-dioxane concentration (i.e., Log(C inf /C eff )). As discussed, the log reduction for runs 1 and <br />2 were negligible. Referring to the test matrix presented in Table 2, runs 3, 4 and 5 were all performed <br />at 0.5 gpm with run 3 at 5 ppm H 2 O 2 , run 4 at 10 ppm H 2 O 2 and run 5 at 20 ppm H 2 O 2 . It is observed <br />in Figure 6 that the log reduction increases as the H 2 O 2 dose increases. Nevertheless, the increase <br />from run 4 at 10 ppm H 2 O 2 to run 5 at 20 ppm H 2 O 2 appears to be quite low. It is important to note <br />that, as reported in Table 2, the effluent concentration for run 5 was below the analytical detection <br />limit of 0.07 µg/L. The corresponding log reduction calculation for run 5 used 0.07 µg/L as the <br />effluent concentration even though the actual concentration was less than 0.07 µg/L. Therefore, the <br />actual log reduction would be some value greater than the 3.45-log reported for run 5 and plotted in <br /> 13