Chong Zhi Kai, Hofmann Alexander, Haye Marie, Wilson Sharon, Sohoo Ihsanullah, Alassali Ayah, Kuchta Kerstin
Circular Resource Engineering and Management (CREM), Hamburg University of Technology, Hamburg, 21073, Germany.
Department of Energy and Environmental Engineering (GEn), Institut National des Sciences Appliquées de Lyon, Villeurbanne, 69100, France.
Open Res Eur. 2024 Jan 22;2:101. doi: 10.12688/openreseurope.14893.3. eCollection 2022.
The acceptance of compostable plastic packaging in industrial composting plants is not universal despite available certification due to the persistence of plastic residues after composting. To better understand this discrepancy, this study compared the disintegration rates of two blends designed for rigid packaging (polylactic acid based) and soft packaging (polybutylene succinate based) in lab-scale composting tests and in an industrial composting plant.
A lab-scale composting test was conducted in triplicates according to ISO 20200 for 4, 8 and 12 weeks to check the disintegration potential of the blends. Duplicate test material were then exposed in the compost pile of an industrial composting plant for a duration of 3 weeks and compared with a supplementary lab-scale test of the same duration.
The rigid packaging samples (1 mm thickness) retained on average 76.4%, 59.0% and 55.7% of its mass after 4, 8 and 12 weeks respectively in the lab-scale. In the plant, the average remaining mass was 98.3%, much higher compared to the average of 68.9% after 3 weeks in the supplementary lab-scale test. The soft packaging samples (109±9 µm sample thickness) retained on average 45.4%, 10.9% and 0.3% of its mass after 4, 8 and 12 weeks respectively in the lab-scale. In the plant, a high average remaining mass was also observed (93.9%). The supplementary lab-scale test showed similar remaining mass but higher fragmentation after 3 weeks.
The results show that the samples achieved significant disintegration in the lab-scale but not in the plant. The difference between the tests that might further contribute to the differing degradation rates is the composition and heterogeneity of the composting substrate. Therefore, the substrate composition and thermophilic composting duration of individual plants are important considerations to determine the suitability of treating compostable plastic in real-world conditions.
尽管有相关认证，但由于堆肥后塑料残渣的残留问题，工业堆肥厂对可堆肥塑料包装的接受程度并不普遍。为了更好地理解这种差异，本研究在实验室规模的堆肥试验和工业堆肥厂中比较了两种用于硬包装（聚乳酸基）和软包装（聚丁二酸丁二醇酯基）的混合物的分解速率。
根据ISO 20200进行了三次实验室规模的堆肥试验，持续4、8和12周，以检查混合物的分解潜力。然后将两份测试材料在工业堆肥厂的堆肥堆中暴露3周，并与相同持续时间的补充实验室规模试验进行比较。
在实验室规模下，硬包装样品（厚度1毫米）在4、8和12周后分别平均保留其质量的76.4%、59.0%和55.7%。在工厂中，平均剩余质量为98.3%，与补充实验室规模试验3周后的平均68.9%相比要高得多。软包装样品（样品厚度109±9微米）在实验室规模下4、8和12周后分别平均保留其质量的45.4%、10.9%和0.3%。在工厂中，也观察到较高的平均剩余质量（93.9%）。补充实验室规模试验显示，3周后剩余质量相似，但碎片化程度更高。
结果表明，样品在实验室规模下实现了显著分解，但在工厂中未实现。可能进一步导致降解速率不同的试验之间的差异在于堆肥基质的组成和异质性。因此，单个工厂的基质组成和高温堆肥持续时间是确定在实际条件下处理可堆肥塑料适用性的重要考虑因素。
