Slide 22 of 24

The results shown above are for variations on the number of sealed drains. The ISBL unit has 97 drains, thus the number of drains approximates the percentage of drains.

In this case, drains were sealed with random placement. VOC emissions decrease as the number of sealed drains increases. The effect is most evident for benzene, which displays a consistent decrease in emissions as the number of sealed drains increases. The highly volatile 1,3-butadiene exhibits little decrease in emissions until at least 70% of the drains are sealed, after which emissions drop rapidly. Methanol does not exhibit significant emissions even for the case without any water seals. The low stripping efficiency of methanol under all the applied conditions indicates that chemicals of low volatility will not have significant emissions from industrial sewer networks.