Importance of the properties, collection, and storage of waste cooking oils to produce high-quality biodiesel – An overview

The collection of Waste Cooking Oils (WCOs) has been growing in recent years due to the increase in society's awareness of environmental aspects since the uncontrolled disposal of WCOs has substantial adverse environmental impacts. WCOs are potential secondary raw materials for producing environmentally friendly biodiesel, which reduces pollution, promotes renewable energy use, and decreases waste. Nevertheless, the presence of several degradation products requires different pre-treatments before their conversion, significantly impacting the economic feasibility of the process. In addition, even pre-treated WCOs may have physical and chemical properties that do not guarantee the production of good-quality biodiesel. Therefore, it is essential to know the degradation reactions occurring during the oil frying and successive storage. Only WCOs that satisfy specific criteria would be used for high-quality biodiesel production. Then, a collection and storage method aimed at biodiesel production should be promoted. The current collection method does not provide for any special measures, storage containers, and temperatures. Instead, it is desirable to have proper collection and storage of WCOs to minimize degradation and have good WCOs before the conversion into biodiesel. Any business generating WCO should be provided with specialized, food grade, stainless steel, or plastic oil storage units that streamline the used cooking oil collection and are ready for scheduled collection. Managing household WCOs appears more complicated, but simple operations such as preliminary filtration and suitable containers can limit undesired reactions with air, light, and humidity, together with a more frequent collection of WCOs by waste disposal companies.