The waste oil received from the restaurant was first
filtered through normal sieve to remove suspended food particles.
Then, it was placed in a cylindrical tank for 24 h and its sediments
and wastes were deposited at the bottom and then were separated
from oil gently. Density of water and impurities were greater than
the oil. To separate the oil from water and solid impurities, longer
times were needed. To accelerate the separation, the oil was heated
for 15 min at 60C temperature and then was transferred into a
precipitation tank for at least 24 h until water and solid impurities
were removed