Study On Removal Of Phosphorus In Wastewater With Natural Minerals And Steel Slag

Phosphate in some industrial wastewater and municipal wastewater is the main reason of eutrophication of reserviors. How to lower the phosphate has been the important task of protecting the water. The paper studied the removal of phosphate in model wastewater and municipal wastewater with natural minerals and industrialwastes-steel slag, analyzed the mechanism of removal of phosphorus and discussedthe feasibility of actual application .Sand did not decrease PO43- concentrations and did not change the pH of the solution. However,as a kind of infiltration media , it played a important role in the treatment of wastewater.Batch tests of limestone showed that it did not effectively remove phosphorus in wastewater and neither the PO43- concentrations nor the pH of the solution changed. Column results indicated that the effluent P concentration was very low when the amount of effluent was relatively small, and then Column would be breakthough quickly.Natural mineral-vermialite did not lower the PO43- concentrations and didnot change the pH of the solution. After being heated in 700 C, it can better remove the phosphate in wastewater. When amount of used 0.5g/100mL, concentration of phosphorus was 10mg/L, under pH 7. 50-7. 60 condition , the remained concentration was under 0. 5mg/L in short time and the efficiency rate of phosphorus removal reached over 99%.Therefore, vermialite can be applied in wastewater treatment, but the process was not steady and this was necessary to continue to study.The results of slag in treating wastewater showed that slag is effective to removal phosphorus. The paper also studied the effects of the amount of slag, time, pH and temperature on phosphorus removal from model wastewater. When concentration of phosphorus was lOmg/L, amount of slag 0. 5g/100mL, under pH 7. 50-7. 60 experimental condition, the concentration of remained is below 0. 1mg/L within 1h and is far below the standard and the efficiency of phosphorus removal rate reached over 99%. Because of the dissolve of CaO, the pH of the solution changed after adding the slag. The difference of the pH before adding the slag in solution resulted in the differencechange of pH and the difference efficiency of removal of phosphorus. The removal of phosphorus is related to the precipitation of Ca-P and adsorption on slag, which caused the most effective removal of phosphorus.Column results of single slag in treating the municipal wastewater showed that slag was effective to removal P04-P and T-P in wastewater. But the dissolve of CaO and formation of large amount of precipitation can cause the clogging of the treatment system quickly. So, it is important to use infiltration media in treatment of the wastewater, and the better efficiency of P removal can be attained throughthe reasonable mixture of infiltration media and the material of P removal.The results of reactive mixtures in treating municipal wastewater showed that they were effective to removal phosphorus in wastewater. The initial P concentration of effluent is small, which is beyond below the standard. But with the increase of the amount of effluent, the P removal effect was changing worse and worse. Because of the large amount CaO in slag, its dissolve caused the high pH of the effluent, which is associated with the better efficiency of removal of phosphorus.It is a kind of economical and effective treatment method to use slag in treating wastewater with phosphorus. This method did not bring about recomtamination . In the meantime, it has a big applicable sense to combine the overall application of wastes with the control of pollution.