Removal of phosphate from aqueous solutions by yellow and red soil from West Azerbaijan and its EDTA-modified form

Phosphorus is a common ion in wastewater treatment effluents, but excess amount of phosphate concentration in the effluent discharge accelerates eutrophication that affects many natural water bodies. Eutrophication of the water bodies is one of the most important environmental problems. Eutrophication can lead to abundant development of aquatic plants, growth of algae and disturbance to the balance of organisms present in the water. Therefore, in present work, natural and modified yellow and red soil with EDTA was used for removal of phosphorous from aqueous solution.
All experiments were conducted in a batch system. Natural yellow and red soil and its modified one with EDTA were used as adsorbent for removal of phosphorous from aqueous solutions. Effect of various experimental parameters such as pH, initial phosphorus concentration, contact time and adsorbent mass were investigated.
Results showed that the removal efficiency was increased by increasing in contact time, adsorbent mass and initial phosphorus concentration. Higher removal efficiency was observed at 150 min contact time, 10 g/L adsorbent mass, 50 mg/L phosphorus concentration and pH 5. At these conditions, about 65% of phosphorus were removed by natural soils, while 78% was removed by modified adsorbents.
The results of present work well demonstrate that, due to higher content of calcium, red and yellow soil is capable for adsorption of phosphorus and if they be modified with EDTA, their efficiency will be improved remarkably.