沉淀硅酸钙晶种法回收实际污水中磷

Recovery of phosphorus in wastewater by crystal seed method of calcium silicate

实验研究了以沉淀硅酸钙为晶种,回收实际污水中磷的效果。结果表明,实际污水磷的质量浓度为25mg/L时,在晶种用量为0.8g/L、pH值为8、Ca/P摩尔比为2的条件下反应2h后,污水中剩余磷的质量浓度为0.81mg/L,低于我国污水综合排放标准(GB8987-1996)一级B标准(1.0mg/L)。反应动力学分析得出,反应速率随着温度升高而增大。采用初始磷质量浓度较高和较低两组实际污水进行沉淀硅酸钙重复回收磷实验,发现污水中较高的磷初始质量浓度有利于磷酸钙结晶,回收效果较好,沉淀硅酸钙重复使用30次后磷的回收率为50%以上。沉淀硅酸钙有望成为回收磷的理想晶种材料。

Tests were carried out on studying the effect of re- covery of phosphorus in wastewater with precipitated calcium sili- cate as crystal seed. The results showed that when mass concen- tration of phosphorus in waste water is 25 mg/L with the dosage of crystal seed being 0.8 g/L, pH value 8 and Ca/P molar ratio 2, reaction takes place for two hours and the mass concentration of remaining phosphorus in waste water is 0. 81 mg/L, lower than Level I B Standard, Integrated Wastewater Discharge Stand- ard in China. Kinetic analysis concluded that the reaction rate in- creases with increasing temperature. Tests on repeated recovery of phosphorus by precipitated calcium silicate for two groups of higher and lower initial mass concentration of phosphorus found that the higher initial phosphorus mass concentration is favorable for crystallization of calcium phosphate with better recovery effect. The phosphorus recovery is 50% and above after repeated use of precipitated calcium silicate for 30 times. The precipitated calcium silicate is expected to be an ideal crystal seed for phosphorus recovery.