Definition: Even carefully made biodiesel has some trace amounts of unreacted lye, methanol and perhaps minute amounts of soap suspended in the fuel. These contaminants reduce the quality of the fuel and can lead to adverse engine performance. Washing biodiesel involves mixing a freshly made batch of biodiesel with an equal amount of water and then allowing the water and fuel to separate. The heavier water will absorb the unreacted agents and sink to the bottom of the washing vessel. The contaminated water is then drained off, leaving clean pure biodiesel behind.
Also Known As: Water Washing, Mist Washing or Bubble Washing
Examples: Commercial biodiesel must be washed to meet ASTM standards.