مهدی محمدی

Water scarcity is one of the most critical global challenges, and with growing demand for freshwater, desalination has emerged as a promising solution. However, conventional desalination technologies are limited by high energy consumption, substantial capital costs and environmental concerns. As an alternative, biological desalination has been gained attention as an efficient and eco-friendly method. In this study, microalgae-based desalination using Chlorella vulgaris (C. vulgaris) was investigated as a sustainable approach to reduce seawater salinity. Mixtures of seawater and BG-11 culture medium were prepared in different ratios, and the effect of algal inoculation levels (10%, 15%, and 20%) on cell growth and desalination performance was evaluated over 21-day period. Optical density (OD) and biomass dry weight were measured as growth indicators, while total dissolved solids (TDS) served as the desalination parameter. The results of a steady increment in OD across all samples confirmed the adaptation of C. vulgaris to the saline conditions. The highest OD (1.744) was obtained for the 15% inoculation on day 21. Significant reductions in TDS were achieved for all treatments, with greater desalination at higher inoculation levels. The maximum reduction occurred with the 20% inoculation on day 13, reaching 32% and 30% for the 75% and 100% seawater treatments, respectively. The results were further supported by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy analyses. Overall, C. vulgaris demonstrated strong potential as an environmentally friendly and innovative strategy for seawater desalination, providing a sustainable complement to conventional methods and new opportunities in industrial water treatment.