土工布处理下酸度对煤矸石淋出液中重金属含量的影响

煤矸石充填塌陷地的传统方法势必造成下部土壤和水资源的重金属污染.在此次柱状淋溶实验中,我们选取聚乙烯丙纶、涤纶针刺、高密度聚乙烯和涤纶复合四种土工布来研究土工布对煤矸石淋出液中重金属迁移的阻隔作用.研究结果表明,四种土工布都能降低淋出液中重金属的含量.由于各种土工布的厚度、材料、生产方法和防渗能力的不同,发现不同土工布对不同重金属的阻隔作用不同,同时发现淋溶介质的酸性不同,对淋出液中各种重金属含量的影响不同.通过分析去离子水淋溶介质和酸性淋溶介质的淋溶结果,得出聚乙烯丙纶土工布能显著降低淋出液中重金属Cr的含量,HDPE土工膜降低重金属Pb和Cu含量的效果显著.在不同的处理效果下,淋出液中Cr、Pb、Cu的含量相对于对照最大能降低50%、47.9%和25.3%.淋出液中各种重金属的浓度与淋出液的pH值之间呈现良好的三次非线性函数关系,且有80%的相关系数大于0.6.与去离子水做淋溶介质的结果相比较,在酸性淋溶介质淋溶过程中,土工布处理下的煤矸石中重金属离子更趋于稳定.重金属Cr,Pb和Cu分别能被聚乙烯丙纶、涤纶针刺和HDPE这三种土工布有效地吸附.涤纶复合土工布将淋出液的pH值稳定在7到7.4之间,更适宜作物生长.土工布功能强大,能够发展成为一项技术被应用到国内矿区土地复垦工程中用来防治污染.

Influences of the Acidity on Heavy Metal Contents in Coal Waste Leachates with Geotextiles

Traditional landfill with coal waste leads to environmental pollution because heavy metals in the leachates of coal wastes can pollute the underlying soil and water.In order to study the pollution abatement of heavy metals with geotextiles,polyethylene-polypropylene geotextiles (PE-PP),fibers needle punched nonwoven geotextiles,high-density polyethylene(HDPE) and fibers geocomposites were chosen in this column test.To a certain extent,four geotextiles can reduce the content of heavy metals in the leachates.Due to the thickness,raw material,producing method and anti-seepage capacity,barrier effects of geotextiles on heavy metals are various.Meanwhile,acidity of the leaching mediums can influence the content of heavy metals in the leachates.Based on synthesizing analysis of the results with deionized and acid water as leaching mediums,PE-PP can significantly reduce the content of Cr in the leachates,HDPE can reduce the content of Pb and Cu effectively. At different disposals,the greatest reduction of the content of Cr,Pb,Cu is 50.0%,47.9% and 25.3% by contrast with that of CK test,separately.The correlation between the concentration of heavy metals and the pH value of leachates greatly fits cubic nonlinear regression with 80% of the coefficients more than 0.6.Compared with the result during deionized water leaching period,heavy metals in the coal wastes may be more stable over acid water leaching period by means of geotextiles.In general,heavy metals of Cr,Pb and Cu can be adsorbed effectively by PE-PP,fibers needle punched nonwoven geotextiles and HDPE,separately.Fibers geocomposites keep pH value of the leachates between 7 and 7.4,more suitable for plants.Multifunctional geotextiles as an effective technology of pollution abatement can be applied into land reclamation engineering in mining areas of China.