Production of Biodiesel from Recycled Grease Trap Waste: A Review

In recent years, climate changes occurring worldwide have encouraged research into the development of eco-friendly, lower-environmental-impact, and more-sustainable energy sources. This may also be a solution to deal with the rapid decrease in, and depletion of, fossil resources. Biodiesel has been considered as a key attribute for effective climate change responses and a potential candidate to substitute for mineral diesel. Even so, the marketability of biodiesel is still very limited, because of the lower price of fossil diesel, as well as the expensive cost of present biodiesel feedstocks. In this regard, the use of wastewater residuals such as scum sludge and grease trap waste (GTW) as a cost-effective feedstock appears to be attractive. Many studies have been conducted to investigate the characteristics of GTW in order to develop an appropriate technique for biodiesel production from this low-quality and low-cost resource. However, most of these studies have only focused on a partial process, including the pretreatment of feedstock, the esterification, and the transesterification processes, without reporting a fully integrated process for biodiesel production from recycled trap grease. Therefore, this study aims to highlight recent achievements in the production of biodiesel from GTW and to consider the potential marketability of this fuel.