Anaerobic digestion of organic waste allows recovering energy and enhancing the subsequent bioplastic degradation in soil

The bioplastics within organic municipal waste are a critical component for the future of waste management with particular reference to the quality of the final products, i.e., digestate and compost. Moreover, to promote a circular economy they need to be recovered to produce new material and/or energy. This study compared polylactic acid (PLA) and starch based (SB) materials which were subjected to anaerobic digestion (AD) treatments producing biomethane, and the fate of residual bioplastics when incubated in soil were then evaluated. Results indicated that AD processes affected both PLA and SB characteristics, influencing their subsequent degradation in soil. Comparative material balance, considering the whole process, indicated that SB bioplastics degraded by 50%, while PLA achieved overall degradation by 70% when thermophilic AD was applied. The insights obtained contribute to understanding the fate of bioplastics and confirmed the role of AD as method for waste valorization in a circular economy perspective.