Abstract: With the implementation of plastic ban policies and the construction of facilities for the resource utilization of food waste, the collaborative treatment of compostable plastics and food waste will inevitably increase. However, there are distinct differences between the standard test conditions for compostable plastics and the actual operating conditions of food waste treatment, and its engineering applicability needs to be verified. This study used compostable plastic bags with a PLA/PBAT/TPS mass ratio of 30∶50∶20. Two practical scenarios were simulated: crushed plastics directly mixed with food waste for aerobic fermentation, and a small amount of plastic residues from enzyme-enhanced pretreatment remaining in food waste for composting. The results showed that in the former scenario, the plastics wound around the stirring shafts of biological treatment equipment. Moreover, the plastics could not be effectively degraded within 9 to 18 months in either household static compost bins or industrial composting systems, indicating severe degradation lag and poor engineering applicability. In the latter scenario, the enzyme-enhanced plastics caused no disturbance to the composting process. After 96 days of composting, the average mass loss rate of individual plastic pieces in a specific calculation method was above 90%. All indexes of the finished compost demonstrated good engineering applicability. Nevertheless, results from scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG) showed that the main chain skeletons of PLA and PBAT in the visible plastic fragments remained intact without fundamental damage.

Key words: compostable plastics, food waste, aerobic fermentation