Use of Saccharomyces cerevisiae as new technique to remove polystyrene from aqueous medium: modeling, optimization, and performance

MPs are widely found in various environments. PS is the second most common microplastic in sediments, freshwater, soil, and coastal ecosystems. S. cerevisiae was studied as a biocoagulant due to its advantages such as ease of use, non-toxicity, large-scale cultivability and low cost. The aim of this study was to evaluate the efficiency of S. cerevisiae in removing PS from aqueous solutions. BBD was used to determine the optimal removal conditions. The MPs were washed, dried, crushed, sieved, and kept in a closed container to avoid exposure to light and moisture. PS removal was measured under various parameters such as the dose of S. cerevisiae (100-300 mg/L), the concentration of PS (200-900 mg/L), and the pH (4-10). The suspension of PS and S. cerevisiae was stirred and subjected to variable speeds to disperse yeast cells and contact with PS particles. The formed clots were settled under static conditions, and the suspended MPs in the aqueous solution were measured by filtering through Whatman filter paper and recording its weight after drying. The maximum PS removal efficiency was 98.81% under optimized conditions, i.e., the PS concentration of 550 mg/L, the yeast dose of 200 mg/L, and the pH of 7. With regard to the mentioned results, it can be said that S. cerevisiae can be used as a natural and environmentally friendly biocoagulant to remove PS.