固体聚硅酸铁铝混凝剂的制备及其混凝除磷研究

以硅酸钠、硫酸铁、硫酸铝、硬脂酸钙为原料,制备了固体聚硅酸铁铝(PSAF)混凝剂,并以桂林市某污水处理厂二级生物处理后的出水为原水,研究了在最佳制备工艺条件下制备的固体PSAF混凝剂投加量和溶液pH对其混凝效果的影响。正交试验结果表明,制备固体PSAF混凝剂的优化工艺条件为:硅酸钠聚合的pH为2.5,溶液硅酸钠的浓度0.4 mol.L-1,Al3+与Fe3+的摩尔比5:5,加入铁铝混合液的温度为30℃,超声时间为40 min,硬脂酸钙的质量浓度为0.10g.L-1;混凝试验结果表明,当原水TP的质量浓度为1.23 mg.L-1、pH为7.5、固体PSAF的最佳投药量为125 mg.L-1时,TP的去除率为91.03%,COD去除率为70.3%,浊度去除率为60%。在pH为6.0～8.0时,固体PSAF除磷效果较好。

PREPARATION OF SOLID POLY ALUMINUM FERRIC SILICATE AND FLOCCULATION REMOVAL PHOSPHORUS

In this paper,solid poly aluminum ferric silicate(PSAF) were prepared by using sodium silicate,ferric sulfate,aluminum sulfate and calcium stearate.The raw wastewater came from effluent of secondary bio-treatment of municipal wastewater treatment plant of Guilin.The factors influencing the removal efficiency of phosphorus from the wastewater,such as the dosage of PSAF and the pH of solution were studied.Orthogonal experiments showed that the optimum preparation process conditions for PSFAS were as follows:Sodium silicate polymerization pH was 2.5,Sodium silicate solution concentration was 0.4 mol·L-1,the Al3+ and Fe3+ molar ratio was 5:5,the temperature of add the mixed liquor of iron and aluminum was 30 ℃,ultrasonic time was 40 min,and the dosage of calcium stearate was 0.10 g·L-1.The results of the coagulating sedimentation showed that when the pH of the solution was 7.48,the phosphorus concentration was 1.23 mg·L-1 after bio-treatment,and the add dosage of PSAF was 125 mg·L-1.The TP removal rate was 91.03%,the COD removal rate was 70.3% and the turbidity removal rate was 60%.At the pH range from 6.0～8.0,the phosphorus removal by Solid PSAF was the best.