Microplastic pollution is a significant threat to aquatic life and human health, yet sustainable remediation options remain limited. Chlorella vulgaris is a potential alternative due to its ability to produce hydrophobic extracellular polymerase substances, allowing it to bond with the microplastics. There is very limited research regarding the specific role that cell density plays in phytoremediation. This study was conducted to evaluate the effect of varied concentrations of microalgae Chlorella vulgaris on the ability to remediate polyethylene microplastics. Chlorella vulgaris concentrations (15 mg/L, 25 mg/L, and 35 mg/L) were prepared using a hemocytometer based cell counting assay. The effect of these concentrations on polyethylene microplastic concentration was then evaluated over four days using a spectrophotometer, and a Beer’s Law Plot. Fluorescent microscopy was used to observe interactions between algae and microplastics. Results were analyzed using a one-way ANOVA and a Tukey post-hoc (p<0.05). 25 mg/L of Chlorella vulgaris was the most effective in microplastic removal (M=7×10-4g/ mm, SD±3.21×10-5) compared to the control (p<0.001). Microscopic imaging revealed that the mechanism of attachment facilitated much of the phytoremediation process. The results demonstrated that Chlorella vulgaris effectively reduced microplastic concentrations, with 25 mg/L being the optimal concentration, possibly as a result of maximal available surface area. The microalgae Chlorella vulgaris showed potential for effective microplastic remediation in aquatic systems. Future researchers may focus on investigating the potential of Chlorella vulgaris in the phytoremediation of other large scale pollutants.

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