Modified Fly Ash Removal Of Phosphorus From Wastewater

Phosphate discharged into the surface waters stimulates the grow of micro and macro aquatic organisms, which in excess can cause eutrophication in stagnant water bodies. Therefore, wastes containing phosphates must meet the discharge limits of phosphates, which is 0.5～1.0mg/L. In order to meet effluent qualify standards, further treatment of effluent is required.The aim of this work was to investigate the possibility of the use of modified fly ash in the removal of phosphorus contained in aqueous solution. The optimum dose of ferrous sulphate has been pursued to modify the fly ash for the maximum removal of phosphorus. A series of batch test were conducted and the influence of temperature, phosphate concentration, solution pH and fly ash dosage on phosphate removal were investigated.The capacity of fly ash without being modified is very limited in removal of phosphorus contained in aqueous solution. Fly ash Modified by ferrous sulphate demonstrated more absorbing ability in phosphate immobilization.The research concluded that the fly ash modified by the optimum dose of ferrous sulphate improved absorption ability in phosphate immobilization. A series of batch test illustrated that the temperature was the dominant factor that affected absorption ability. The higher the temperature of the solution, the more phosphorus can br absorbed from 20 ℃ to 60℃.Results show that some adsorption conditions infuence the efficiency of phosphorus removal greatly. As to the simulated wastewater studied in this research, the optimum conditions for adsorption of phosphorus are: fly ash dose is 2. 5g/100mL～3. 5g/100mL; absorption time is 30min; pH of the solution is from 4 to 10; higher temperature is better. Adsorbent doses of modified fly ash 2. 5 and 3. 5g/100ml produced over 98% and 99% removal...