They use multiple effect evaporation with energy integration etc. MED as you refer in desalination is peculiar here you use series of single stage flash. Feed is fermented was containing about 10% alcohol, Vapors are ethanol+ water primarily and Concentrate is Stillage / vinasse/ spent wash. So they use it very much. We did it in 1996 while I was working at Praj Industries Limited. Visit their website. But then it all depends on economics, technically it has been done many a times especially when you have fermented wash from non molasses source and you want a concentrated stillage.