乙酸钠强化溶析结晶处理废水中高浓度硝酸盐的研究

Experimental Investigation on Treatment of High Concentrations of Nitrate in Wastewaters with Sodium Acetate Anhydrous by Reinforcement Elution Crystallization Method

针对工业生产过程产生的高浓度硝酸盐废水,或者反渗透、离子交换后的高浓度硝酸盐废水,提出了利用无水乙酸钠强化无水乙醇溶析结晶法去除高浓度硝酸盐的技术。考察了无水乙醇、无水乙酸钠、氧化钙、温度、pH以及搅拌速率对硝酸盐结晶的影响,并对比了加入无水乙酸钠前后去除溶液中NO_(3)^(-)-N的效果。结果表明:NO_(3)^(-)质量浓度为183.5 g/L(即NO_(3)^(-)-N质量浓度为49.4 g/L)时,去除NO_(3)^(-)-N的最佳去除条件为,80 mL无水乙醇,1.8 g无水乙酸钠,0.014 g氧化钙(Ca^(2+)质量浓度为1.00 g/L),温度为40℃,pH为13;与无水乙醇溶析结晶处理高浓度硝酸盐废水相比,无水乙酸钠会进一步提高硝酸盐结晶率约10个百分点,说明后加入无水乙酸钠对无水乙醇溶析结晶去除高浓度硝酸盐具有明显的强化作用。

For high concentrations of nitrate wastewater from the industrial production process,or the high-concentration nitrate wastewater after reverse osmosis and ion exchange,a technology of using sodium acetate anhydrous to strengthen the elution crystallization method with ethanol to remove high concentration of nitrate was proposed.The effects of absolute ethanol,anhydrous sodium acetate,calcium oxide,temperature,pH,and stirring rate on nitrate crystallization were investigated,and the effects of removing NO_(3)^(-)-N in the solution before and after sodium acetate anhydrous addition were compared.The results showed that when the mass concentration of NO_(3)^(-)is 183.5 g/L(that is the mass concentration of NO_(3)^(-)-N is 49.4 g/L),the best removal conditions of NO_(3)^(-)-N are:absolute ethanol of 80 mL,sodium acetate anhydrous of 1.8 g,calcium oxide of 0.014 g(Ca^(2+)mass concentration is 1.00 g/L),temperature of 40℃,and pH=13.Compared with the treatment of high concentration of nitrate wastewater by elution crystallization method with ethanol,the sodium acetate anhydrous will further increased the nitrate crystallization rate is about 10%.This result showed that the addition of sodium acetate anhydrous has a significant strengthening effect on the removal of high-concentration nitrate by elution crystallization method with ethanol.