Hydraulic and sorption performances of soil amended with calcium-magnesium composite powder against natural arsenic contamination
Hydraulic and sorption performances of soil amended with calcium-magnesium composite powder against natural arsenic contamination
复制标题
DOI：
10.1016/j.sandf.2020.05.007
复制
发表时间：
2020-08
影响因子：
3.7
通讯作者：
Jialin Mo;G. Flores;T. Inui;T. Katsumi
中科院分区：
文献类型：
--
作者：
Jialin Mo;G. Flores;T. Inui;T. Katsumi
挖掘的土壤和岩石含有来自地质来源的有毒金属和/或类金属，通常在建筑工地大量产生。而这些有毒金属和/或类金属在开挖后的淋溶是一个主要的环境问题，其浓度较低，但高于环境标准。吸附层法是一种经济有效的对策，用于处理和再利用这些挖掘的土壤和岩石。该方法利用路堤底部具有吸附能力的渗透性土壤层，以保留溶解在渗滤液中的相关化学品。清洁的宿主土壤通常被用作吸附层材料，并添加有毒的金属固定剂以增强吸附性能。研究了风化花岗岩土壤经钙镁复合粉改良后作为吸附层材料对砷（As）自然污染的吸附效果。通过批式吸附试验、导水率试验和上向流柱渗滤试验，对复合材料的水力和吸附性能以及配合比和养护时间的影响进行了沿着评价。结果表明，当添加量为5%时，吸附性能提高了15倍，导水率保持在1 × 10− 6 m/s左右。无论是液压也不吸附性能的强烈影响固化期长达28天。在批量吸附试验中，随着钙镁试剂的添加量增加至5%，吸附性能增加。由于土壤-试剂混合物的渗透性水力性质，具有改善的吸附能力，表明它是一种有前途的材料，用于与吸附层方法一起使用，用于处理大量低污染水平的土壤。
Excavated soils and rocks, containing toxic metals and/or metalloids from geogenic sources, are usually generated in huge volumes at construction sites. And the post-excavation leaching of these toxic metals and/or metalloids with low concentrations, but higher than the environmental standards, is a major environmental concern. A sorption layer method was developed as a cost-effective countermeasure for treating and reusing such excavated soils and rocks. The method utilizes a permeable soil layer, with sorption capacity at the bottom of the embankment, to retain the chemicals of concern that have dissolved in the leachate. Clean host soil, amended with toxic metal-immobilizing agents, is often used as the sorption layer material to strengthen the sorption performance. This study examined the feasibility of applying decomposed granite soil, amended with calcium-magnesium (Ca-Mg) composite powder, as the sorption layer material against the natural contamination of arsenic (As). The hydraulic and sorption performances, along with the effect of the mix proportions and curing periods, were evaluated through batch sorption tests, hydraulic conductivity tests, and up-flow column percolation tests. The results showed that the sorption performance increased by 15 times when using an additive content of 5% Ca-Mg and that hydraulic conductivity was maintained at around 1 × 10−6m/s. Neither the hydraulic nor the sorption performance was strongly affected by curing periods up to 28 days. The sorption performance increased with the addition of the Ca-Mg agent of up to 5% in the batch sorption tests. The permeable hydraulic property, with an improved sorption capacity due to the soil-agent mixture, indicated that it is a promising material for use with the sorption layer method for treating huge amounts of soils with low levels of contamination.