硅酸钙晶种法回收污水中磷的实验研究

实验研究了以钾长石水热分解的副产物沉淀硅酸钙为晶种,回收模拟污水中磷的效果。结果表明,晶种用量0.4 g/L、p H值为8、Ca/P(摩尔比)=2条件下反应2 h后,污水中剩余磷浓度为0.32 mg/L,低于我国污水综合排放一级A标准0.5 mg/L。沉淀硅酸钙重复使用60次后回收磷的效果仍然较好,回收率为79.5%以上。采用扫描电镜、红外光谱、粉晶X射线衍射等测试手段对回收产物进行的分析表明,回收磷产物以羟磷灰石形态存在,产物中P2O5含量在35%以上,达到了富磷矿的品位。沉淀硅酸钙有望成为回收磷的理想晶种材料。

Calcium silicate-seeded crystallization for phosphorus recovery from wastewater

With synthetic wastewater, the authors investigated phosphorus recovery effect by seeded crystallization of precipitated calcium silicate, which is a byproduct of feldspar hydrothermal decomposition. The results showed that the remaining effluent phosphorus concentration could meet the wastewater discharge standard of 0.5 mg/L under the optimized conditions of seed concentration of 0.4 g/L, pH value of 8 and Ca/P molar ratio of 2. Phosphorus recovery efficiency of 79.5% showed that phosphorus recovery effect was still obvious after the precipitated calcium silicate was used for sixty times. The products obtained were analyzed by using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) techniques. The results show that the product of phosphorus recovery is hydroxyapatite (HAP). P₂O₅ content of more than 35% shows that the product can meet the standard of the rich phosphate rock and the precipitated calcium silicate is a potential and perfect seed of phosphorus recovery.