Biodegradation of polybutylene adipate terephthalate and polyvinyl alcohol within aquatic pathway

Understanding the environmental fate of biodegradable plastics in aquatic systems is crucial, given the alarming amount of plastic wastes and microplastic particles transported through aquatic pathway. Furthermore, there is a need to analyze the biodegradability of commercialized biodegradable plastics upon release from wastewater treatment plants into natural aquatic systems. This study investigates the biodegradation behaviors of polybutylene adipate terephthalate (PBAT) and polyvinyl alcohol (PVA) in wastewater, freshwater, and seawater. Biodegradation of PBAT and PVA assessed via BOD experiment, microcosm test, and subsequent FT-IR analysis revealed that the type of aquatic systems governs the biodegradation behaviors of each plastic, with the highest biodegradation rate achieved in wastewater for both PBAT and PVA (25.6 and 32.2% in 30 d, respectively). Plastic release route from wastewater into other aquatic systems simulated by sequential incubation in different microcosms suggested that PBAT exposed to wastewater and freshwater before reaching seawater was more prone to degradation than when directly exposed to seawater. On the other hand, PVA displayed similar biodegradability whether directly or indirectly exposed to seawater. Metagenome amplicon sequencing of microbial community revealed distinct shifts depending on the environment and type of plastic, with notable differences along the aquatic pathway. Our findings underscore the significant influence of pollution routes on the biodegradation of PBAT and PVA, highlighting the potential for wastewater treatment to facilitate rapid degradation compared to direct exposure to pristine aquatic environments.