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Figure 6. Similarly, runs 6, 7 and 8 were all performed at 1 gpm with 5, 10 and 20 ppm H 2 O 2 doses respectively. For these runs we observe that the log reduction values increased from 1.17-log at 5 ppm to 1.91-log at 10 ppm and to 2.64-log at 20 ppm H 2 O 2 . Runs 9, 10 and 11 were performed at 2 gpm again with 5, 10 and 20 ppm H 2 O 2 dose targets. The measured 1,4-dioxane log reduction values for these runs increased from 0.63-log to 0.98-log and to 1.39-log with increasing H 2 O 2 dose. These results show that by increasing H 2 O 2 dose from 5 ppm to 10 ppm resulted in an average log reduction increase of 63% while increasing from 10 ppm H 2 O 2 to 20 ppm H 2 O 2 resulted in an average log reduction increase of 40% (based on runs 7, 8, 10 & 11). This is the expected result in that there is a diminishing benefit to contaminant log reduction due to H 2 O 2 dose increases. This is because although increasing the H 2 O 2 concentration increases the rate of hydroxyl radical generation it also increases the rate of hydroxyl radical scavenging by H 2 O 2 . The results presented in Figure 6 also illustrate that the measured 1,4-dioxane log reduction increases as the flow rate decreases. Analyzing the data presented in Figure 6 and Table 2 indicates that reducing the flow rate by 50% results in an average log reduction increase of 83%. This is also consistent with expectations because it is known that UV reactor efficiency can decrease at low flow rates due to poor hydraulic flow patterns (i.e., poor mixing) in the reactor leading to broad UV dose distributions. Figure 6: Summary of 1,4-Dioxane Log Reduction Data Another method of describing the treatment performance is to examine the electrical energy per order (E EO ) parameter for 1,4-dioxane, as described previously. The E EO is calculated by dividing the UV electrical power by the flow rate and by the 1,4-dioxane log reduction. Therefore, lower E EO values 14