Care must be taken to avoid the formation of emulsions during the washing steps, since they would reduce the efficiency of the process.
The first washing step is carried out with acidified water, to neutralize the mixture of esters.
Then, two additional washing steps are made with water only.
Finally the traces of water must be eliminated by a drying step.
After drying, the purified product is ready for characterization as biodiesel according to international standards.