Waste Cooking Oil Case Study

and esters. In the case of hydrolytic reaction, the steam produced during the processing of food containing water causes the hydrolysis of triglycerides, resulting in the formation of free fatty acid, glycerol, monoglycerides, and diglycerides. High free fatty acid level, i.e. quantum of free fatty acids greater than 1 mg/g KOH, results in generation of high amounts of undesirable soap simultaneously with transestrification reaction. In the alkali-catalyzed process, the presence of free fatty acid (greater than 1 mg/g KOH) and water in the oil can cause high amounts of undesirable soap formation, also consuming some quantity of alkaline catalyst and reduces the effectiveness, all of which result in a lower conversion. Therefore, for the feedstock with high free fatty acids, it is essential to have a pretreatment stage before subjecting it to transesterification process.[16]

1.2 Pretreatment Process for Waste Cooking Oil
Pretreatment of waste cooking oil consists of physical treatment for removing the suspended solid contaminants and chemical treatment processes mainly for deacidification. A flow sheet giving the different approaches for pretreatment of waste cooking oil is shown in Figure 2. Issariyakul et al. Have reported the treatment of waste cooking oil using centrifugation for the removal of solid portions of the oil. Water was

However, this method has been modified suitably under controlled conditionsand has become an industrial tool for partial separation of fatty acids. Temperature-controlled crystallization has been used inthe industry to separate the oleic acid rich fraction from amixture of oleic and linoleic acids. The main disadvantage of this process is poor separation, as the separation is only based on the solidification point, resulting in the contamination of each fraction of the acids with high levels of other acid