多种介质修复磷石膏堆场渗滤液污染岩溶地下水

Remediation of Karst Groundwater by Percolation of Phosphogypsum Yard with Various Media

磷石膏堆场渗滤液对岩溶地下水的污染是亟待解决的重要问题。利用石灰石、沸石、膨润土、钢渣四种介质对磷石膏堆场渗滤液污染的岩溶地下水进行处理,分析了不同介质与粒径条件下的处理效果,并筛选出高效、无二次污染的处理介质及最佳粒径。结果表明,添加Ca(OH)_2调高pH有利于岩溶地下水中PO_4^(3-)、F^-、SO_4^(2-)、Mg、Fe、Mn的去除,Fe、Mn、Mg浓度均低于检测限;石灰石、沸石、膨润土、钢渣对PO_4^(3-)的去除率均在98.0%以上,对F-平均去除率分别为93.3%、94. 1%、88.8%、89.1%,对SO_4^(2-)平均去除率分别为74.1%、70.7%、73.3%、79.6%,选用石灰石、膨润土、沸石作为反应介质。通过粒径筛选实验,150目膨润土、3～16目石灰石、16～32目沸石处理后的岩溶地下水中Fe、Mn、Mg浓度均低于检测限,PO_4^(3-)、F^-、SO_4^(2-)去除率分别为99.3%、91.6%、73.1%,99.7%、87.1%、84.0%,99.3%、87.5%、65.8%。通过实验初步确定选用150目膨润土、3～16目石灰石、16～32目沸石作为处理介质。研究结果可为磷石膏堆场渗滤液污染的岩溶地下水修复提供重要的基础数据。

Contamination of leachate from phosphogypsum dump to karst groundwater is an important problem to be solved urgently. Limestone,zeolite,bentonite and steel slag were used to treat the karst groundwater contaminated by the leachate in this study,and the treatment effects under different mediums and particle sizes were analyzed,by which efficient mediums without secondary pollution and optimum particle sizes were selected. The results show that lime added to adjust p H is favorable to removal of PO4^3-,F-,SO4^2-,Mg,Fe and Mn from karst groundwater. After processing,the concentrations of Fe,Mn and Mg were,in turn,were lower than the detection limits. The removal rates of PO4^3- by limestone,zeolite,bentonite and steel slag were all over 98.0%,the average removal rates of F-were 96.3%,96.7%,93.8% and 93.9% respectively,and those of SO4^2- were 74.1%,70.7%and 73. 3% separately. Therefore,limestone,bentonite and zeolite were selected as reaction mediums. Then,through the medium particle size screening experiment,the optimum particle size combination was determined as150 mesh bentonite,3 ~ 16 mesh limestone and 16 ~ 32 mesh zeolite. The results show that the removal rates of PO4^3- by them were 99.3%,89.6% and 73.1%,those of F-were 99.7%,85.8% and 84.0%,and those of SO4^2- were 99.3%,88.1% and 65.8%. After processing,the concentrations of Fe,Mn and Mg were all lower than the detection limits. The experimental results can provide important basic data for the remediation of karst groundwater contaminated by leachate in phosphogypsum dump.