【摘要】 实验模拟地下环境,以天然矿物材料石灰石、海泡石和膨润土作为可渗透反应墙(PRB)填充材料,采用正交实验法设计了16种可渗透反应器,研究了天然矿物组合材料组配对污染地下水模拟液中镉污染的修复效果、出水pH、有效孔隙度和渗透系数的影响,同时对机理进行了分析。实验结果显示,组合材料对镉去除率达99.8%以上,石灰石对处理效果贡献最大,增加石灰石用量,处理效果明显改善,当石灰石含量为10%及更高时,对含镉1.0 mg/L的污染地下水模拟液处理后镉浓度低于0.7μg/L,达到地下水质量标准GB/T 14848-93规定的II类水质标准;石灰石用量的增加对渗透系数影响不大,但出水pH呈弱碱性(7<pH<9),随反应时间延长逐渐降低并稳定于8。增加海泡石和膨润土用量对处理效果改善作用不大,但显著降低体系渗透系数,影响透水性。以正交实验直观分析法计算得到修复效果最优的PRB填充材料组配为石灰石/海泡石/膨润土=20/10/2(质量分数)。更多还原

【Abstract】 In this work,the combination materials of natural minerals including bentonite,sepiolite and limestone were used as permeable reactive barrier(PRB) filling materials and 16 permeable reactors were designed with orthogonal test method to study the feasibility and efficiency of the PRB technology in the remediation of cadmium contaminated ground-water. The influences of the combination ratio of the minerals on the treatment effect of Cd contamination,the pH of effluents,the porosity and permeability of the barriers were studied. Moreover,the remediation mechanism was also analyzed. The experimental results showed that the Cd removal rates of the applied combination materials were above 99. 8%. The dosage of limestone was the main factor controlling to the treatment effect of Cd,which was obviously improved by increasing the amount of limestone. When the limestone content reached 10%,the Cd concentration of simulated Cd-polluted ground-water after treatment was less than 0. 7 μg/L, which can meet the class II water quality standard according to groundwater quality criteria(GB/T 14848-93). Increasing the amount of limestone had little effect on the permeability of the barrier,but it led to a weakly alkaline effluent(7 < pH <9). The pH of the effluent slowly decreased to about 8 as the reaction continued. Increasing the dosage of sepiolite and bentonite could slightly improve the treatment effect,but it would significantly decrease the permeability of barrier. The optimal composition of the filling materials for PRB obtained with the orthogonal designdirect analysis method was 20% of limestone,10% of sepiolite and 2% of bentonite in mass.更多还原