Department of Civil and Environmental Engineering, University of Firenze, Firenze, Italy.
Department of Chemistry 'Ugo Schiff' and CSGI, University of Firenze, Firenze, Italy.
Waste Manag Res. 2022 Aug;40(8):1311-1321. doi: 10.1177/0734242X211063731. Epub 2021 Dec 4.
The present research investigates the degradation rate of bioplastics under various composting conditions, including suboptimal ones. Lab-scale tests were carried out setting three variables: temperature (37°C-58°C), humidity (30%-60%) and duration of the thermophilic and the maturation phases (15-60 days). The composting tests were carried out following modified guideline ISO 20200:2015 and lasted for 60 days. Bioplastics in the synthetic waste matrix consisted of Mater-Bi film biobags and PLA rigid teaspoons. A kinetic study was performed, resulting in faster degradation rates for film bioplastics (first-order kinetics with = 0.0850-0.1663 d) than for rigid (0.0018-0.0136 d). Moreover, film bioplastics reached a complete degradation within the 60 days of the test. Concerning the rigid products, 90% degradation would be achieved in 2-3 years for mesophilic conditions. Finally, in the undersieve of 0.5 mm some microplastics were identified with the ImageJ software, mainly relatable to rigid (PLA) bioplastics. Overall, the results disclosed that the combination of mesophilic temperatures and absence of moistening slowed down both the degradation and the disintegration process of bioplastics.
本研究考察了在各种堆肥条件下，包括条件不佳的情况下，生物塑料的降解速率。进行了实验室规模的测试，设定了三个变量：温度（37°C-58°C）、湿度（30%-60%）以及高温和成熟阶段的持续时间（15-60 天）。堆肥测试按照修改后的 ISO 20200:2015 指南进行，持续 60 天。合成废物基质中的生物塑料由 Mater-Bi 薄膜生物袋和 PLA 刚性茶匙组成。进行了动力学研究，结果表明薄膜生物塑料的降解速度更快（一级动力学， = 0.0850-0.1663 d），而刚性生物塑料的降解速度较慢（0.0018-0.0136 d）。此外，薄膜生物塑料在测试的 60 天内完全降解。关于刚性产品，在中温条件下，90%的降解将在 2-3 年内实现。最后，在 0.5 毫米的筛子下，用 ImageJ 软件识别出一些微塑料，主要与刚性（PLA）生物塑料有关。总体而言，研究结果表明，中温条件和缺乏润湿会减缓生物塑料的降解和崩解过程。
