硫酸根对颗粒铁去除铬动力学影响研究

铁渗透反应格栅是铬污染地下水的有效去除技术,但地下水中SO42-对铁格栅长期运行性能影响还不清楚。文章采用批实验和柱实验的方法,分别研究了硫酸根离子浓度对颗粒铁从液相去除常量C(rVI)(20mg/L)的动力学影响及这种影响随时间的变化。批试验表明,随SO42-浓度的增加,C(rVI)的面积标准化速率系数kSA增加。柱试验采用三个平行柱实验系统连续输入含20mg/LC(rVI)的模拟地下水(含或不含SO42(-1000mg/L))。柱实验表明,运行100PV以前,SO42-显著增大颗粒铁对C(rVI)的面积标准化速率常数kSA,随后SO42-增强作用逐渐减弱,运行337PV时,SO42-没有明显的影响。硫酸根离子通过在铁表面形成配合物而加速铁的溶解,增加颗粒铁的表面活性,从而增强颗粒铁对C(rVI)的去除,生物作用不强时可以不考虑硫酸根对铁格栅长期运行性能的影响。

Effects of Sulfate Ion on Hexavalent Chromium Removal Dynamics by Granular Iron

Iron permeable reactive barriers are effective remediation of groundwater contaminated by hexavalent chromium.However the impact of major ions in groundwater such as sulfate on permeable reactive barriers is unclear.The effect of sulfate on removal dynamics with chromium concentration (20mg/L)was investigated by mixed batch and column experiment.Batch experiments showed observed Cr(VI) reduction rate increased with increasing sulfate concentration.Column tests included three parallel systems input with simulated groundwater containing 20mg/L Cr(VI),with or without sulfate at 1000mg/L.Column results showed that sulfate can make surface area normalized coefficients of hexavalent chromium removal by granular iron increase before 100PV.Subsequently the enhancement of sulfate became weaker.Based on nearly 400PV,it was unnecessary to consider the sulfate effect on long-term performance of reactive barrier without obvious biological activity.