Anaerobic Degradation of PLA Bioplastic: Effect of Pretreatment Methods on Biogas Production Efficiency and Biodegradability

In recent decades, bioplastics have gained increasing attention as an alternative material to conventional petroleum-based plastics due to their biodegradability, which contributes to reduced environmental pollution. After their use, bioplastics can be transformed into environmentally friendly products, such as compost, or energy carriers as biogas. This study investigates the short-term batch anaerobic biodegradability of polylactic acid (PLA) bioplastics accessible to household consumers, explores the impact of various pretreatment techniques on the anaerobic digestion process, and assesses the potential of PLA as a sustainable source of energy. Anaerobic digestion of thermally or biologically pretreated PLA, as well as of a PLA–ethyl acetate mixture, at 46.3 ± 0.5 °C resulted in a biogas yield ranging from 139.20 ± 22.14 to 510.26 ± 9.92 L/kg of raw material. However, PLA mass loss analysis indicated that a short-term 25-day digestion period was insufficient for complete biodegradation. Furthermore, considering the biogas production dynamics, it is unlikely that a longer digestion period would have significantly increased the biodegradation degree. Depending on the pretreatment method applied, the degree of PLA biodegradation after anaerobic processing ranged from 12.87% to 26.46%.