Abstract

Objective: To investigate the biodegradation of high density polyethylene (HDPE) by Streptomyces species isolated from the soil of East Azerbaijan, Iran. Methods: Powders of HDPE samples were prepared by grinding in different particle sizes of 212, 300, 420, and 500 microns. Each time 50 mg of a sample was poured to a liquid medium containing species. Samples were incubated for 18 days at 28 °C in a shaker-incubator and their degradation percentage was measured by weighting method. Produced metabolite at 18th day was analyzed by gas chromatography-mass spectrometry. Also a film of HDPE was subjected to biodegradation and after one month was analyzed by scanning electron microscope which showed degradation on the surface of the film. Results: The results showed that Streptomyces species degraded 50 mg of HDPE sample with the size of 212 μm about 18.26%, 300 and 420 μm about 14.4%, and 500 μm about 13%. Kinetic modeling of biodegradation process showed that the reaction rate was first order with respect to concentration of HDPE. Based on gas chromatography-mass spectrometry results, no high toxic material was produced during biodegradation of HDPE. Conclusions: The research showed that isolated Streptomyces sp. are capable of degradation of HDPE polymer with high degradation efficiency.

Authors and Affiliations