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.
What do I do with my glycerin?
There are many options:
- Recover your methanol from the glycerin and make raw soap with The De-methylation Trio.
- Make soap (and an online biodiesel soap-making book).
- 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.
- 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.
- Use it as a composting agent. See the Dickinson College study.
- Use it as a dust suppressant.
- 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.