Mist Washing Biodiesel

Mist washing is the gentlest form of water washing biodiesel. This method decreases the chances of emulsification because it does not agitate the mixture as much as bubble washing or stir washing.


How it Works:

The mister produces a fine spray above the biodiesel, gently covering the surface. The water slowly seeps its way down through the biodiesel (since water is the heavier of the two). As the water descends, it collects the contaminants which all end up in the wastewater layer at the bottom of the wash tank. The wastewater is then drained and the process begins again until a pH test of the waste water indicates the biodiesel is clean.


Supplies Needed:

• Mist head to fit on hose

• Hose

• Wash tank

• Outlet drain for wash water

• pH strips to tell when the biodiesel is clean


How to Mist Wash:

* Adding hot water (between 120°F and 150°F) makes washing biodiesel more effective and deters emulsions. One idea is to connect a hose to a hot water heater.

* Either rig an automatic shutoff for the water, or pay close attention so that your tank doesn’t overflow!

Set up the mist head far enough above the biodiesel so a fine mist will gently fall on the surface, but not break the surface tension.

Turn on the water, and let it mist for a couple of hours or until the mixture is 1/3 water and 2/3 biodiesel.

Turn the water off, and let the mixture settle for an hour or more.

Drain the wash water off the bottom and repeat the process with fresh water until the water you are draining is the same pH as when it entered (this indicates no more contaminants are being removed).

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