CaCl2与纳米SiO2-聚硅酸铝铁复合混凝剂

采用CaCl₂和纳米SiO₂-聚硅酸铝铁复合混凝剂对含氟废水进行两步除氟。实验结果表明：ρ（ F^–）为 420.0 mg/L、pH为8.5的含氟废水经CaCl₂处理后ρ（ F^–）降至26.5 mg/L;在二级除氟pH为11.5、复合混凝剂加入量（复合混凝剂与废水体积比）为0.50%的最佳条件下处理60 min后废水中ρ（ F^–）降至5.7 mg/L,而采用聚合氯化铝（PAC）进行二级除氟时,ρ（ F^–）可降至8.7 mg/L,表明复合混凝剂比PAC的除氟效果更佳。复合混凝剂中自由离子和单体羟基配合物形态Al和Fe的含量相对较高,分别占76.5%和92.5%,而低聚合度的多核羟基配合物及高聚物形态Al和Fe的含量相对较低。

Treatment of high fluoride-containing wastewater using CaCl2 and nano SiO2-polysilicate aluminum ferric composite coagulant

CaCl₂ and SiO₂-polysilicate aluminum ferric composite flocculant were used for two-stage fluoride removal from fluoride-containing wastewater,respectively. The experimental results indicated that：The ρ（ F^–）of the wastewater was declined from 420.0 mg/L to 26.5 mg/L by CaCl₂ addition at pH 8.5;Under the optimum conditions of pH for the second-stage fluoride removal 11.5,amount of the composite flocculant 0.50% （volume ratio of composite flocculant to wastewater）and treatment time 60 min,the ρ（ F^–）was decreased to 5.7 mg/L,however,when polyaluminum chloride（PAC）was used for the second-stage fluoride removal,the ρ（ F^–）was declined to 8.7 mg/L,which indicated that the removal effect of the composite flocculant was better than that of PAC. The contents of Al and Fe with free ion form and monomer hydroxyl complex form in the composite flocculant were relatively higher,accounting for 76.5% and 92.5% respectively,while those with low-polymerization-degree polynuclear hydroxyl complex form and high polymer form were relatively lower.