Glycerin Layer in Biodiesel Production

What to Do With Your Glycerin Layer

What is the glycerin layer (aka "glycerin")?
Glycerin is the byproduct left over after the biodiesel reaction process is complete. In a BioPro™ 190, at the end of the two-step reaction process, there will be 50 gallons of biodiesel in the main tank resting above 10-12 gallons of glycerin. (In the BioPro™ 380, this will be 100 gallons of biodiesel atop 20-24 gallons of glycerin).
This glycerin is usually dark brown and has a thicker viscosity than reacted biodiesel which is usually a honey brown color. Before moving to the wash cycle, your glycerin must be drained out of the tank at the ball valve and captured in a separate container.

Turning fat into money (via biodiesel processing)

What do I do with my glycerin?
There are many options:

  1. Recover your methanol from the glycerin and make raw soap with The De-methylation Trio.
  2. Make soap (and an online biodiesel soap-making book).
  3. Feed your glycerol to cattle: Feeding glycerin to ruminants; Glycerin as a potential feed ingredient for dairy cattle;  Glycerol, a byproduct of the biodiesel industry, in livestock feeds, Glycerin confirmed as a feasible foodstuff for cattle.
  4. Take it to a sewage treatment plant where they have an “anaerobic digester”. Though they probably won't pay you for it, they do welcome the stuff.
  5. Use it as a composting agent. See the Dickinson College study.
  6. Use it as a dust suppressant.
  7. Burn it.

Note: There are things you should not do with your glycerin. You should never dump it into a stream or down the drain. Glycerin will kill fish and other aquatic creatures due to its high BOD (Biological Oxygen Demand) rate.