Assessment of methane production, disintegration, and biodegradation potential of bioplastic waste in anaerobic digestion systems

The suitability of bioplastics for treatment in anaerobic digestion and composting plants is not always clear despite their increasing popularity as an alternative to oil-based polymers. This study aims to estimate the anaerobic degradation of various combinations of bioplastics (cellulose acetate, polylactic acid (PLA) and polybutylene succinate (PBS)), filler (organic – gelatine – and inorganic) and plasticizer (triacetin) combinations, under conventional industrial digestion conditions. The investigation encompasses the evaluation of both physical (disintegration) and biological degradation processes, along with the modelling of their methane production utilizing various iterations of the Gompertz-type model. Results indicate that, during typical industrial residence time, cellulose-based bioplastics exhibit high methane yield (approximately 500 NmlCH4/gVS) and near-complete degradation (both physical and biological), while PLA has minimal biodegradation (11%) and low methane yield (59 NmlCH4/gVS). PBS-gelatine blends generate a significant amount of methane early in the digestion process (174 and 116 NmlCH4/gVS for flakes and pieces, respectively) but do not achieve full degradation. These findings suggest that the effectiveness of bioplastics degradation varies based on their composition, and further research is needed to optimize their treatment in common industrial facilities.