Factors affecting degradation of bioplastics in composting facilities and identification of compost core microbiome
Organic residues in food packaging impair conventional plastic recycling. Whenever food contamination is inevitable, compostable packaging offers a preferrable solution. In line with this, EU regulations mandates industrial compostability for items such as fruit labels, permeable tea, coffee, or beverage bags starting in February 2028. However, knowledge about how biodegradable plastic impacts composting performance in different composting facilities remains limited. In this study, eight different industrial composting facilities and citizen home composts were systematically investigated. We included bacterial and fungal community composition, temperature, moisture, pH and carbon to nitrogen ratio. The impact of polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polyhydroxy butyrate (PHB), poly(butylenadipate-co-terephthalate) (PBAT) and polybutylene succinate (PBS) bioplastics on composting characteristics together with their biodegradation was investigated. Our study reveals that industrial composting facilities share a common core microbiome dominated by Bacillota which is only marginally affected by bioplastic amendment at 20 wt%. Further, we identified a biodegradation optimum for PHB and PHBH at 40°C, pH 5 and a moisture of 50% and could identify increased PLA degradation rates with a closed architecture, namely Box-type composting material, characterized by the highest measured temperatures. Bioplastics did not affect the pathogenic potential of compost samples and thermophilic composting phases eliminates all identified pathogens enhancing the biosafety of compost-derived fertilizer in agriculture. By widening our understanding of composting conditions that can influencing bioplastic biodegradation, the knowledge from this study could eventually support stakeholders in the composting value chain towards optimal composting conditions and bioplastics properties.
Organic residues in food packaging impair conventional plastic recycling. Whenever food contamination is inevitable, compostable packaging offers a preferrable solution. In line with this, EU regulations mandates industrial compostability for items such as fruit labels, permeable tea, coffee, or beverage bags starting in February 2028. However, knowledge about how biodegradable plastic impacts composting performance in different composting facilities remains limited. In this study, eight different industrial composting facilities and citizen home composts were systematically investigated. We included bacterial and fungal community composition, temperature, moisture, pH and carbon to nitrogen ratio. The impact of polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polyhydroxy butyrate (PHB), poly(butylenadipate-co-terephthalate) (PBAT) and polybutylene succinate (PBS) bioplastics on composting characteristics together with their biodegradation was investigated. Our study reveals that industrial composting facilities share a common core microbiome dominated by Bacillota which is only marginally affected by bioplastic amendment at 20 wt%. Further, we identified a biodegradation optimum for PHB and PHBH at 40°C, pH 5 and a moisture of 50% and could identify increased PLA degradation rates with a closed architecture, namely Box-type composting material, characterized by the highest measured temperatures. Bioplastics did not affect the pathogenic potential of compost samples and thermophilic composting phases eliminates all identified pathogens enhancing the biosafety of compost-derived fertilizer in agriculture. By widening our understanding of composting conditions that can influencing bioplastic biodegradation, the knowledge from this study could eventually support stakeholders in the composting value chain towards optimal composting conditions and bioplastics properties.
Institute of microbiology Leibniz University Hannover