Nitrate (NO3-) and phosphate (PO43-) removal from aqueous solutions by microalgae Dunaliella salina

This study was conducted to investigate the mechanism involved in the removal of nitrate (NO3-) and phosphate (PO43-) by microalgae, Dunaliella salina from aqueous solutions through a series of batch experiments and FT-IR analyses. The effect of various operation parameters including pH of the solution, microalgae dosage, initial NO3- and PO43- concentrations and interference of other cations and anions on the uptake capacity and removal efficiency of D. salina was evaluated. The NO3- and PO43- concentrations were measured with spectrophotometric methods. The results showed that the maximum adsorption of NO3- and PO43 with using D. salina as adsorbent were 332 and 544 mg g(-1) and the best removal efficiency ofNO(3)(-) and PO43 were obtained 54% and 82%, respectively. These results were obtained at pH 7, 0.05 g L-1 biomass dosage of microalgae and 350 mg L-1 of initial NO3- and PO43- concentrations. The experiments of reusing adsorbent material thought adsorption-desorption cycling showed that the reuse ability of this algae for phosphate desorption is higher than nitrate. Also, the removal efficiency and uptake capacity were decreased in the presence of other interfering anions and cations, except for NaCl, which showed a positive effect on the uptake capacity of phosphorus by algae. The results of this investigation suggested that D. salina biomass is suitable as an adsorbent material for recovery and adsorption of NO3- and PO43- ions from aqueous solutions.