Techno-economic assessment of waste poly(lactic acid) enzymatic hydrolysis and recycling for poly(lactic acid) production

To maintain the increasing consumer demand for plastics, more sustainable production methods are required in parallel to innovative recycling methods to reduce the disposal of waste plastics. Lactic acid (LA) derived from enzymatic hydrolysis of waste poly(lactic acid) (PLA) can be used for PLA production. Thus, this study compared the profitability of six PLA production scenarios through Aspen Plus® simulations and techno-economic analysis. Three PLA production pathways were investigated: no hydrolysis of waste PLA (base case), low (50 %) and high (90 %) enzymatic conversion of waste PLA. The LA from PLA hydrolysis was combined with virgin LA in both decentralized and centralized settings. For the decentralized setting, the minimum selling price (MSP) of PLA in the base case (1.75 US$/kg) was 6–8 % lower than for scenarios utilizing waste PLA. For the centralized settings, the MSP in the base case (2.70 US$/kg) was similar to the scenarios utilizing waste PLA. Both settings were below market price (5.14 US$/kg), meaning both settings were profitable, and PLA production from enzymatically hydrolyzed waste PLA was deemed cost-competitive with PLA from virgin LA.