Anaerobic biodegradation of biopolymers for sustainable valorization of bioplastics: Integrated kinetic modeling and microbial community assessment.

Anaerobic biodegradation of bioplastics has gained increasing attention as a sustainable strategy for waste valorization and renewable energy recovery within circular bio-economy systems. The present study investigated the anaerobic biodegradation of Poly lactic acid (PLA) pellet, PLA film, Polybutylene succinate (PBS), and commercially available bioplastics under controlled conditions at different temperatures and incubation periods. Biodegradation behavior was evaluated through cumulative gas production, visual observations, FTIR characterization, kinetic modeling, and microbial analysis. All biopolymer samples exhibited significant cumulative gas production within 20 days before reaching the stationary phase. Among the biopolymer materials, PLA film showed distinct degradation behavior with high total solids (92.5%) and volatile solids (75.4%), along with the highest cumulative gas production. FTIR analysis and observable structural changes further confirmed polymer degradation during anaerobic digestion. Microbial species associated with biodegradation were identified through PCR amplification, 16S rRNA sequencing, and phylogenetic analysis, revealing the involvement of Bacillus sp in the degradation process. The cumulative biogas production profiles of all biopolymers followed the Hill sigmoidal kinetic model with high correlation coefficients (R2: 0.9854, 0.9839, 0.9931, and 0.9772 for PLA pellet, PBS, PLA film, and bioplastic, respectively), indicating excellent model fitting accuracy. Moreover, a generalized anaerobic biodegradation model equation was developed for biopolymers. The findings demonstrated the potential applicability of anaerobic digestion for biopolymer waste valorization through simultaneous biodegradation and biogas generation, supporting sustainable waste management and circular bio-economy approaches.