Development of microbial consortia for valorizing post-consumer polyethylene via thermal-biological process: The Plastic Biorefinery

Polyethylene (PE) is the most produced plastic globally. Its short lifespan as single-use plastic makes it one of the most abundant plastic wastes; thus, it is imperative to look for PE biorefinery approaches. Combining thermal and biological treatment opens the window for PE upcycling to valuable products, e.g., biochemicals and biopolymers. Regarding this approach, PE was subjected to pyrolysis to produce PE pyrolysis wax. NMR study showed that PE wax composes mainly of paraffins (74.95% (v/v)) and olefins (21.53% (v/v)). To enhance the functionality of hydrophobic PE wax, a microbial consortium obtained from plastic landfill soil through long-term enrichment on PE wax was applied as a biocatalyst to modify it into solubilized products. Preliminary results showed that the enriched consortium has a short lag phase (22.6 h) on PE wax and can biodegrade 89% of PE wax within 7 days. The increase of soluble products after exposing PE wax to microbial consortia was shown by the higher intensity of peaks between the chemical shift of 3.6 to 4.7 ppm, observed by 1H NMR. This study aims to further develop the microbial consortia by adaptive laboratory evolution to intensify PE wax metabolization at high concentrations. The constant increase of PE wax concentration will be performed to promote substrate utilization rate and tolerance toward PE wax. The combination of pyrolysis and functional microbial consortium could facilitate to the valorization of highly abundant polyolefin post-consumer waste by upcycling PE into higher-value products.