Municipal biowaste treatment plants contribute to the contamination of the environment with residues of biodegradable plastics with putative higher persistence potential

Abstract

Biodegradable plastics (BDP) are expected to mineralize easily, in particular under conditions of technical composting. However, the complexity of the sample matrix has largely prevented degradation studies under realistic conditions. Here composts and fertilizers from state-of-the-art municipal combined anaerobic/aerobic biowaste treatment plants were investigated for residues of BDP. We found BDP fragments > 1 mm in significant numbers in the final composts intended as fertilizer for agriculture and gardening. Compared to pristine compostable bags, the recovered BDP fragments showed differences in their material properties, which potentially renders them less prone to further biodegradation. BDP fragments < 1 mm were extracted in bulk and came up to 0.43 wt% of compost dry weight. Finally, the liquid fertilizer produced during the anaerobic treatment contained several thousand BDP fragments < 500 µm per liter. Hence, our study questions, if currently available BDP are compatible with applications in areas of environmental relevance, such as fertilizer production.

Influence of Poly-3-hydroxybutyrate Micro-Bioplastics and Polyethylene Terephthalate Microplastics on the Soil Organic Matter Structure and Soil Water Properties

“…Notably, it is assumed that PHB will be used extensively in the future, meaning that its increasing input into the soil (mulch, delivery systems, coatings, or littering) can also be expected. Therefore, it is important to be aware of possible problems that may arise as a result of its use in agriculture or in other industries . The aim of this work was not to frame PHB as a new contaminant but rather to underscore the observation that the potential problems that bioplastics may cause in soil should be comprehensively investigated rather than overlooked.…”

“…Therefore, it is important to be aware of possible problems that may arise as a result of its use in agriculture or in other industries. 75 The aim of this work was not to frame PHB as a new contaminant but rather to underscore the observation that the potential problems that bioplastics may cause in soil should be comprehensively investigated rather than over-looked. Future studies should thus aim to develop recommendations as to how such problems with bioplastics in agriculture might be avoided as bioplastics currently seem to be the only way to address the soil microplastics problem.…”

Performance of Biodegradable Biochar-Added and Bio-Based Plastic Clips for Growing Tomatoes

“…However, some biodegradable plastics, e.g., biodegradable foils, under realistic conditions can persist in the environment for several years. It has not been concluded whether these biodegradable plastic materials in different environments undergo mineralization or just disintegrate into smaller particles [ 27 ]. Therefore, laboratory composting of the CUT clips should be validated under realistic conditions, e.g., in a composting facility.…”

Frontiers in soil ecology—Insights from the World Biodiversity Forum 2022

“…Furthermore, the recent surge in high‐resolution remote‐sensing products has been less expansive for soil properties, due to the inherent issues related to assessing belowground conditions from space. For several other, less common drivers, such as pesticides (Beaumelle et al, 2021; Edlinger et al, 2022; Riedo et al, 2021), antibiotics, other—often new—chemical substances, such as PFAS (perfluoroalkyl and polyfluoroalkyl substances), heavy metals and microplastics (Rillig et al, 2019; Steiner et al, 2022), global coverage is even lower: Assessing and predicting underrepresented drivers : Importantly, while assessment of the current levels and implications of most of these environmental conditions is scattered at best, many of them are also rapidly changing under global change. Assessments of ongoing changes, let alone predictions of future changes or reconstructions of past changes, are rare even for soil temperature (Lembrechts & Nijs, 2020) and nonexistent at the large scale for most of the other environmental parameters covered above.…”

“…Furthermore, the recent surge in high-resolution remote-sensing products has been less expansive for soil properties, due to the inherent issues related to assessing belowground conditions from space. For several other, less common drivers, such as pesticides (Beaumelle et al, 2021;Edlinger et al, 2022;Riedo et al, 2021), antibiotics, other-often new -chemical substances, such as PFAS (perfluoroalkyl and polyfluoroalkyl substances), heavy metals and microplastics (Rillig et al, 2019;Steiner et al, 2022), global coverage is even lower:…”