A Novel Approach for the Biological Desalination of Major Anions in Seawater Using Three Microalgal Species: A Kinetic Study

The global water shortage alert has been upgraded to a higher risk level. Consequently, a sustainable approach for ecofriendly, energy efficient water desalination is required for agricultural and municipal water reuse. In this study, an energy-efficient biological desalination process was used to treat chloride anions, which are the most abundant anion salt in seawater. Three algal species were studied: Scenedismus arcuatusa ( S. arcuatusa ), Chlorella vulgaris ( C. vulgaris ), and Spirulina maxima ( Sp. maxima ), under different operating conditions (saline concentrations, contact time, high light intensity, and CO 2 supply), and two kinetic models were used. It was identified that under a high light intensity and CO 2 supply, S. arcuatusa enhanced chloride removal from 32.42 to 48.93%; the daily bioaccumulation capacity (Q e ), according to the kinetic models, was enhanced from 124 to 210 mg/g/day; and the net biomass production was enhanced from 0.02 to 0.740 g/L. The EDX analysis proved that salt bioaccumulation may be attributed to the replacement of Ca 2+ and Mg 2+ with Na + and K + through algal cells. The study’s findings provide promising data that can be used in the search for novel energy-efficient alternative ecofriendly desalination technologies based on algae biological systems with biomass byproducts that can be reused in a variety of ways.