Fragmentation and Mineralization of a Compostable Aromatic–Aliphatic Polyester during Industrial Composting

Abstract

Compostable plastics support the separate collection of organic waste. However, there are concerns that the fragments generated during disintegration might not fully biodegrade and leave persistent microplastic in compost. We spiked particles of an aromatic−aliphatic polyester containing polylactide into compost and then tracked disintegration under industrial composting conditions. We compared the yields against polyethylene. The validity of the extraction protocol and complementary microscopic methods (μ-Raman and fluorescence) was assessed by blank controls, spike controls, and prelabeled plastics. Fragments of 25−75 μm size represented the most pronounced peak of interim fragmentation, which was reached already after 1 week of industrial composting. Larger sizes peaked earlier, while smaller sizes peaked later and remained less frequent. For particles of all sizes, count and mass decreased to blank level when 90% of the polymer carbon were transformed into CO 2 . Gel permeation chromatography (GPC) analysis suggested depolymerization as the main driving force for disintegration. A transient shift of the particle composition to a lower percentage of polylactide was observed. Plastic fragmentation during biodegradation is the expected route for decomposing, but no accumulation of particulate fragments of any size was observed.

Certified Compostable Products and Sustainable Food Waste Management via Laboratory-Level Simulation Anaerobic Digestion and Postdigestion Composting

“…This indicates that CO 2 accounts for the majority of the total mass of the degradation products of compostable plastic composting. Other studies have also demonstrated this characteristic of compostable plastics . These experiments showed that certified compostable plastics that have gone through the AD biodegrade faster in the postdigestion composting step in comparison to certified compostable plastics that did not go through the AD process before composting.…”

The power of centrifugation: How to extract microplastics from soil with high recovery and matrix removal efficiency

“… Fragment recovery tests using a biodegradable polymer powder : For method development, it was first checked, if any microplastic loss in the sediment would occur during centrifugation. For this purpose, we compared centrifugation with 1.6 g/cm 3 SPT solution to centrifugation with 1.8 g/cm 3 SPT solution and found 168 (1.6 g/cm 3 ) and 51 (1.8 g/cm 3 ) microplastic particles per gram LiHof C11 soil in the sediment using fluorescence microscopy for the analysis (the method description can be found in our previous study [1] ). The original spiking was 50 mg biodegradable fragments in 2 g of LiHof C11 soil, corresponding to about 4500–5000 particles by using the known size distribution and polymer density for calculation, assuming spherical particles.…”

“…To determine the microplastic recovery, the cryomilled polymer powder was added to 2 g of soil and intensively mixed into the soil by using a spatula. For real world samples it is recommended to use a mixing device (e.g., TurbulaSystem Schatz T2F [1] ) for homogenization and subsampling. Soil agglomerates are broken apart during the ultrasonication step.…”

“…For protocol development a prelabeled biodegradable polyester blend (ecovio® PS1606, BASF SE, ρ = 1.25 g/cm 3 ) was used for visual inspection and for recovery tests with the final protocol. As described in our previous publication, the prelabeled blend was synthesized by compounding 3 kg of the biodegradable polyester with 3 g of the fluorescence dye Lumogen F Yellow 083 (BASF SE, 0.1 % in weight) at 180 °C on a mini-extruder Rheomex CTW 100 [ 1 ]. In the next step, the polymer granules were cryomilled using a Retsch ZM 200 ultra centrifugal mill.…”

Trendbericht Analytische Chemie 2024

“…Neben qualifizierten Probennahmen und Probenvorbereitungen in Kombination mit mikroskopischen und spektroskopischen Methoden ist es auch notwendig, bestehende Standards anzupassen. [71][72][73][74] Die digitale Transformation hat das Potenzial, analytische Fragen, Arbeitsweisen und Labore grundlegend zu verändern. Labore haben…”