Distillation would probably take care of most of the contaminants, I would think. It would require monitoring the temperature of the distillation flask so that you could discard the stuff that boiled off below 100 degrees celsius, which would be the volatile organics (including ethanol, if you get really, really lucky in your contaminants), and stop collecting the stuff that boils at temps over 100 c. ( Disclaimer: this is based upon 2 semesters of organic chem 40 years ago, when the periodic table was a lot smaller and life was simpler; midway through the second semester, I blew up part of the lab in completing an assigned experiment involving nitro-toluene).