Valorization of urban waste oil by microbial conversions

The irregular disposal of urban waste oils (UWO) from homes and commercial establishments directly in sewers has become a major environmental concern nowadays. In the last years, intensive research has been carried out to seek alternatives to reduce disposal and to properly use UWO. In a search using the Scopus database with “waste cooking oil” OR “waste oil” OR “waste frying oil” OR “residual cooking oil” OR “residual frying oil” OR “residual oil” as queries (title, abstract, and key-words) from 2020 to Jully 2021, the production of biodiesel using UWO was the most frequent topic of manuscripts related to the use of this waste (43.8%). Beside this, a wide range of bioproducts with industrial interest can also be obtained using super-processed oils, such as emulsifiers, esters, bioplastics, biolubricants, among others. This review focus on the production of lipase and biosurfactants, which are bioproducts with great industrial application potential. According to the Scopus search, performed including “enzyme production” as query, lipase is the most prominent enzyme produced from UWO, and the yeast species Y. lipolytica is mainly used in those processes. One to five percent of UWO titer is used in lipase production medium, and many investigations are focused on developing co-production processes to obtain other bioproducts simultaneously. Most of the biosurfactants produced from UWO were identified as glycolipids, mainly rhamnolipids, and they are generally applied to remove oil from soil and water contamination sites.