PDF(Pubmed)
Abstract：
This study investigates the feasibility of biocementing clay soil underneath a railway embankment of the UK rail network via carbonic anhydrase (CA) biocementation, implementing the treatments electrokinetically. Compared to previous biocementation studies using the ureolytic route, the CA pathway is attractive as CA-producing bacteria can sequester CO2 to produce biocement. Clay soil samples were treated electrokinetically using biostimulation and bioaugmentation conditions to induce biocementation. The effects of the treatment were assessed in terms of undrained shear strength using the cone penetration test, moisture content, and calcium carbonate content measurements. Scanning electron microscopy (SEM) analyses were also conducted on soil samples before and after treatment to evaluate the reaction products. The results showed that upon biostimulation, the undrained shear strength of the soil increased uniformly throughout the soil, from 17.6 kPa (in the natural untreated state) to 106.6 kPa. SEM micrographs also showed a clear change in the soil structure upon biostimulation. Unlike biostimulation, bioaugmentation did not have the same performance, although a high amount of CaCO3 precipitates was detected, and bacteria were observed to have entered the soil. The prospects are exciting, as it was shown that it is possible to achieve a considerable strength increase by the biostimulation of native bacteria capturing CO2 while improving the soil strength, thus having the potential to contribute both to the resilience of existing railway infrastructure and to climate change mitigation.
摘要：
这项研究调查了通过碳酸酐酶（CA）生物固井在英国铁路网的铁路路堤下生物固井粘土的可行性，电动实施治疗。与以前使用尿素溶解途径的生物固着研究相比，CA途径是有吸引力的，因为产生CA的细菌可以隔离CO2以产生生物细胞。使用生物刺激和生物增强条件对粘土土壤样品进行电动处理，以诱导生物沉积。使用圆锥贯入试验，根据不排水剪切强度评估处理效果，水分含量,和碳酸钙含量测量。还对处理前后的土壤样品进行了扫描电子显微镜（SEM）分析，以评估反应产物。结果表明，在生物刺激下，土壤的不排水抗剪强度在整个土壤中均匀增加，从17.6kPa(在天然未处理状态下)到106.6kPa。SEM显微照片还显示了生物刺激后土壤结构的明显变化。与生物刺激不同，生物强化没有相同的性能，尽管检测到大量的CaCO3沉淀物，观察到细菌已经进入土壤。前景令人兴奋，因为它被证明是可能的，通过生物刺激天然细菌捕获CO2，同时提高土壤强度，以实现相当大的强度增加，因此，有可能为现有铁路基础设施的复原力和缓解气候变化做出贡献。
