Anaerobic digestion and aerobic composting of rigid biopolymers in bio-waste treatment: fate and effects on the final compost

Bioplastics may be collected in the bio-waste treatment, which is often composed of anaerobic digestion and subsequent aerobic composting of the digestates. The aim of this study was to evaluate the degradability of polylactic acid (PLA) and starch-based bioplastics (SBB) spoons under industrial conditions. Biomethane potential (BMP) was measured and biogas production was monitored, while the quality of composts was assessed by phytotoxicity and ecotoxicity tests. The bioplastics disintegration resulted in 65.1 +/- 4.6 % for PLA and <= 65.0 +/- 7.4 % for SBB, not achieving the target set by UNI EN 13,432 standard, and several residues were found in compost. Phytotoxicity tests on seeds reported the lowest Germination Index for PLA elutriate, whereas a potential negative effect of SBB on soil fauna was detected. Further investigation is needed to assess the fate of these ever-growing materials under industrial conditions, and also evaluate the effects of residues in compost.

Automated summary

This study evaluated the degradability of polylactic acid (PLA) and starch-based bioplastics (SBB) under industrial conditions. The results showed that the disintegration of these bioplastics did not meet the standard requirements, with residues found in compost. Phytotoxicity tests indicated that PLA elutriate had the lowest Germination Index, while SBB had a potential negative effect on soil fauna. Further investigation is needed to understand the fate of these materials in industrial conditions and assess the effects of residues in compost.