Valorization of PE plastic waste into lipid cells through tandem catalytic pyrolysis and biological conversion

Worldwide plastic pollution challenges the existing recycling technologies. Upcycling approaches that can convert plastic waste into value-added products are necessary for the creation of a circular plastics economy. This study demonstrated a process concept to convert Polyethylene (PE) waste into microbial lipid through tandem catalytic pyrolysis and biological conversion by oleaginous yeast Yarrowia lipolytica. PE waste was catalytically pyrolyzed into small molecular hydrocarbons, which were further digested by oleaginous microorganism to accumulate lipid. Through catalyst selection, fermentation intensification, and strain adaptive evolution, a lipid production of 122 mg/L was obtained using pyrolysis oil as sole carbon source. Through the whole process, approximate 15 % of PE was converted into lipid cells. This upcycling process was evaluated through carbon footprint analysis. Cell production, lipid content, and electricity consumption are the main factors influencing the process carbon emission. Sensitivity analysis showed that a carbon reduction can be achieved with the improvement of these parameters. This tandem process establishes a sustainable strategy for the conversion of plastic waste into value-added products.