Bioremediation of low-density polyethylene microplastics using red microalga porphyridium purpureum: a biotechnological perspective

In the present study, the biodegradation of Low-Density Polyethylene microplastics was investigated using Porphyridium purpureum microalgae, with a focus on evaluating the effects of microplastic concentration, particle size, and shaking speed. The study was conducted in two phases: first, optimizing the cultivation conditions for Porphyridium purpureum, followed by assessing its ability to remove Low-Density Polyethylene. The highest microalgae yield was achieved under optimal conditions, which included a light intensity of 2500 µmol photons m⁻² s⁻¹, F/2 culture medium, and a temperature of 30 °C. These conditions were established as the baseline for the Low-Density Polyethylene removal phase. The results demonstrated that the maximum Low-Density Polyethylene removal efficiency achieved was 34.24%. Fourier Transform Infrared Spectroscopy analysis demonstrated a reduction in the intensity of the carbonyl functional group, likely due to the release of carbon from the microplastic structure, thereby indicating an effective interaction between microalgae and Low-Density Polyethylene. Furthermore, Scanning Electron Microscopy images revealed significant surface modifications, including small holes and corrosion on the Low-Density Polyethylene particles, providing strong evidence of the degradation process facilitated by Porphyridium purpureum. These findings suggest that the microalgae have the potential to degrade Low-Density Polyethylene microplastics, offering valuable insights into their use for bioremediation of microplastic pollution.