Purification of phosphate contained wastewater by modified fly ash

The purification of phosphate contained wastewater by sulfuric acid modified fly ash was investigated to determine the effect of pH,adsorbent dosage,reaction time and temperature on purification efficiency.The results showed that the optimum pH for phosphate removal was 9.The removal percentage of phosphate increased with increasing the adsorbent dosage.When the initial phosphate concentration was 193.30 mg/L and the adsorbent dosage was 30 g/L,the phosphate concentration would decreased to 0.91 mg/L,gave the removal percentage of 99.53%.The adsorption of phosphate by modified fly ash was highly effective,for the maximum purification efficiency could be achieved in 5 min.There was a relatively wide temperature range for the adsorption process,and the effect of temperature on removal efficiency was negligible when it ranged 20-40 ℃.The adsorption data were well fitted by Freundlich isotherm model with the 1/n was 0.374,the results revealed that it was feasible to remove phosphate from the waste water by the modified fly ash.