It isn't a chemical reaction. It is a physical process.
NaCl, being ionic, bonds with the water molecules, thus competing with ethylene glycerol (EG) for H-bonding sites for water. Moreover, NaCl may form H bonds with EG, thus making EG less readily to form H bonds with water.
If no H bonding sites are available, then EG should seperate from the mixture.
I suggest NaCl because it is chemically inert, unless heavy metal ions are present.
You ought to experiment this in the lab before actually carrying it out even on a pilot plant scale.
Moreover, the centrifugation technique suggested by Eugenedakin must be carried out in an open flow process. It will not work in a batch configuration because EG will remix with water as soon as the centrifugal force is no longer applied.