> From there, it's pretty easy to filter out the soil and clean it up.
"Cleaning" soil is an interesting concept. At what point does it just become dirt? Presumably some of the nutrients will remain, but it seems like this would sterilize it.
Dirt still has use, of course, but soil is expensive to produce for a reason.
Well, cleaning in this case would be removing the remaining DMSO, which is probably not too desirable to have in your soil.
Considering the existing DDT contamination, ending up with dirt that needs to be fortified with compost is hardly the worst trade-off.