The production of biodiesel from edible oils competes with the
use of land for food production. Moreover, the price of edible
plant and vegetable oils is usually higher than petro diesel.
Thus, finding a cheaper feedstock such as waste cooking oil
for biodiesel production reduces the cost of biodiesel production
since the feedstock costs constitutes approximately 70–
95% of the overall cost of biodiesel production. Hence, the
use of waste cooking oils and non-edible oils should be given
higher priority over the edible oils as biodiesel feedstock
(Chhetri et al., 2008; Canakci, 2007). The purity level of the
biodiesel has strong influence on its fuel properties.