Very Dilute Ethanol Recovery from Water

[nstarbard]

I was wondering if anybody knows a company or method that could potentially recover ethanol present at only 0.1 wt% in water. The stream is extremely large (flowrate of around 700-800 GPM). I am only looking to get the stream up to maybe 3-5 wt% ethanol. Right now I am thinking pervaporation with membranes. One problem is the recovery and efficiency as far as I can tell varies greatly from membrane type to membrane type, and often those composites are only offered from a specific company. If anybody has experience with this or has contact info Id appreciate it.

 

[siretb]

I wonder if liquid liquid extraction followed by distillation would be economically feasible

 

[25362]

Could gas stripping under special conditions be of help ?

See, for example:

www.shu.edu.cn/journal/vol1no2199717.htm​

 

[bimr]

The whole ethanol industry is searching for the same solution. That's why people some claim that it takes more energy to produce ethanol than what is derived from ethanol.

 

[bonzoboy]

Would activated carbon work? Try the Calgon people, up in Pittsburgh. Ethanol is probably large enough molecule to get stranded on the high surface area carbon.

 

[moltenmetal]

You're fighting entropy here in a very big way. Give up.

Pervaporation will be so energy-intensive that there's no way it would pay. Same goes for more conventional methods like stripping etc. Carbon won't work- the molecule is small and it's miscible with water.

Even if you could recover part of the energy cost by reducing disposal or water treatment cost, your cause is hopeless. There's too little value in the product ethanol to justify processing such an enormous quantity of water.

 

[dalcazar]

I agree completely with moltenmetal, the flow rate is just too big to justify recovering that small an ammount of ethanol. No matter what you use to treat it, the investment in equipment and energy will never make economic sense.

where is this flow coming from? you might be a lot better off optimizing part of the process upstream of the point you're describing.