Study of brown algae Sargassum biomass in bio-absorption of various concentrations of nitrate

The excessive entry of nitrate from municipal wastewaters and agriculture to surface and sub-surface water resources leads to the formation of the eutrophication phenomenon, followed by the algal bloom and the decreases of dissolved oxygen in aquatic ecosystems. These changes reduce the biological balance of these ecosystems and ultimately the death and destruction of living organisms. Currently, various adsorbents are used to remove excess of nitrate ion from aqueous solutions. In this study, marine algae, Sargassum ilicifolium was studied as a bioabsorbent for removal of nitrogen ion. In this experiment, various range of pH including (pH 2, 3, 4, 5, 6, 7 and 8), the amount of algae biomass S. ilicifolium (0.01, 0.3, 0.05, 0.1, 0.15, 0.2, 0.3 and 0.4 g) and the initial concentration of ion nitrate (50, 100, 150, 200, 250, 300 and 350 mg L -1) at contact time (0-60 minutes) on removal of nitrate ions from aqueous solution was investigated. Nitrate concentration was measured by spectrophotometric method at 500 nm wavelength. The results of this experiment showed that marine macro algae, S. ilicifolium had the best nitrate absorption capacity of 560 mg g-1 in the most suitable conditions, and the nitrate removal efficiency was 48%. The most suitable conditions for nitrate absorption were obtained at 0.01 g L -1 algae biomass, pH: 7 and 350 mg L-1 of initial nitrate concentration. The results of this study showed that the dry powder of algae, S. ilicifolium is suitable for removal of nitrate ions from aqueous solution and is an appropriate bioactive agent for urban and agricultural wastewater treatment.