Anaerobic Biodegradation of Polylactic Acid-Based Items: A Specific Focus on Disposable Tableware Products

The viability of anaerobic degradation treatment as an end-of-life option for commercial disposable bioplastic tableware, typically certified as compostable, was assessed. Two types of polylactic acid-based items were selected and tested under mesophilic conditions (38 °C) for 155 days, until reaching a plateau. Advanced chemical characterization of the products was performed with a combination of analytical techniques, i.e., microscopy, spectroscopy, and thermogravimetry. Two methods for calculating the biodegradation degree of the products were discussed and compared, using the biogas generated in the test and the total organic carbon (TOC) removal, respectively. The method based on TOC removal, resulting in a biodegradation degree ranging from 80.5% to 88.9%, was considered to more accurately describe the process. Given the complexity of assessing the biodegradation of a bioplastic product, an effort was made to derive correlations among the chemical-physical composition of the product, the biodegradation conditions, and the biodegradation yields/kinetics, with an aim to describe the process comprehensively. Statistical tools were also applied to derive additional considerations regarding the influence of the polymeric blend and digestion parameters on the biodegradation of bioplastic products. The identified data clusters, which were found to be grouped by the digestion temperature and the type of bioplastic, indicated specific biodegradation features of the investigated materials.