Degradation of polypropylene-poly-L-lactide blends by Bacillus isolates: a microcosm and field evaluation

Abstract

Degradation of the blends of polypropylene (PP) and poly-L-lactide (PLLA) by bacterial isolates in soil microcosm and field environment was studied. Five Bacillus strains (B. cereus (P3) and P13), B. thuringenesis (P8 and P10) and B. licheniformis (P6)) isolated from composted samples were used in this study. In microcosm, polymer blends were buried in soil augmented with bacterial isolates and studied bacterial population and degradation ability. The bacterial population (cfu/g soil) increased with time where maximum growth was observed in consortium. The formation of bacterial biofilm was observed on the surface of polymers. FTIR analysis revealed breakage of carbonyl bonds in polymeric blends and thermal stability of the blends decreased as observed through TGA analysis. Field experiment was carried out by burying the blends in an open-field augmented with bacterial consortium for 6 months. Mechanical strength and thermal stability of blends decreased in bacterial treated samples than control. These results suggest that Bacillus species enhances degradation of polymeric blends and can be used in remediation technologies for waste management practices.