Sustainable valorization of waste cooking oil into biofuels and green chemicals: Recent trends, opportunities and challenges

Food waste reduction and utilisation are paramount to achieve the United Nations (UN) goals for sustainable development. The exploitation of food waste valorization into green chemicals, materials and biofuel is crucial to curtail the economic and environmental impact of food waste disposal. Specifically, WCO is considered as a major stream of the food waste that has high concentration of lipids that are easily reachable. The approachable lipids in WCOs have boosted the research on valorization technologies to produce biofuels and green chemicals. Biodiesel has been reported as the major product of WCO utilisation using various catalytic and non-catalytic techniques. On the other hand, the valorization of WCO into sustainable oleo-chemical products has captured high interest from different researchers. This chapter highlights the main progress and developments in WCO valorization technologies into biofuels and oleo-chemical products including biodiesel, biojet fuels, bio-lubricants, surfactants, asphalt rejuvenator, plasticizers, etc. This work has a main focus on both catalytic and non-catalytic production processes of biodiesel from WCO. Challenges in up-scaling and commercialising the developed technologies have been addressed. Finally, recommended bio-refinery approaches to integrate WCO processes with other technologies have been discussed.