摘要：

为探究高盐废水中除硬和除硅的最佳条件，分别进行了双碱法混凝除硬实验和铝剂混凝除硅实验，结合单独除硬和除硅结果进行了加药混凝同时除硬除硅的实验，并研究了同步加药法和分步加药法对除硬除硅效果的影响。结果表明，双碱法混凝除硬的最优条件为NaOH、Na₂CO₃投加量分别为450、1 100 mg/L，Ca²⁺、Mg²⁺去除率分别为91.5%和83.5%；铝剂混凝除硅的最优条件为pH=8、NaAlO₂投加量为600 mg/L，全硅、Si_a和Si_c的去除率分别为90%、92%和80%；同步加药法中Ca²⁺、Mg²⁺去除率与单独除硬实验基本一致，而全硅、Si_a和Si_c去除率分别仅为39.8%、37.3%、40.3%；分步加药法先加入除硅药剂去除SiO₂，再加入除硬药剂去除硬度，全硅、Si_a和Si_c去除率与单独除硅实验基本保持一致，而Ca²⁺、Mg²⁺去除率分别为91.5%和88.3%，Mg²⁺去除率较单独除硬实验略有上升。分步加药法可高效同时去除高盐废水中的硬度和硅，在实际工业应用中具有较好前景。

关键词: 高盐废水, 除硬, 除硅, 混凝沉淀, 分步加药法

Abstract:

In order to explore the optimal removal conditions of hardness and silicon in high-salt wastewater, double alkali method coagulation for hardness removal experiment and aluminum agent coagulation for silicon removal experiment were carried out respectively. Combined with the results of individual hardness and silicon removal, experiments were conducted on the simultaneous hardness and silicon removal by adding coagulants, and the effects of synchronous and step-by-step dosing methods on the effect of hardness and silicon removal were studied. The results showed that the optimal conditions for hardness removal by double alkali coagulation were 450 mg/L NaOH and 1 100 mg/L Na₂CO₃, respectively, and the removal rates of Ca²⁺ and Mg²⁺ were 91.5% and 83.5%, respectively. The optimal conditions for aluminum coagulation were pH=8, NaAlO₂ dosage of 600 mg/L, and removal rates of all-silicon, Si_a and Si_c were 90%, 92% and 80%, respectively. The removal rates of Ca²⁺ and Mg²⁺ in synchronous dosing method were basically consistent with the results of individual hardness removal experiment, while the removal rates of all-silicon, Si_a and Si_c were only 39.8%, 37.3% and 40.3%, respectively. In the step-by-step dosing methods, the agent for silicon removal was first added to remove SiO₂, and then the agent for hardness removal was added to remove hardness. The removal rates of total silicon, Si_a and Si_c were basically consistent with that of individual silicon removal experiment, while the removal rates of Ca²⁺ and Mg²⁺ were 91.5% and 88.3%, respectively. The removal rate of Mg²⁺ was slightly higher than that of individual hardness removal experiment. The step-by-step dosing method could efficiently and synchronously remove hardness and silicon from high salt wastewater, which had a good prospect in practical industrial application.

Key words: high-salt wastewater, hardness removal, silicon removal, coagulation and precipitation, step-by-step dosing method

中图分类号: 

• X703