论文标题
细菌密度对微生物诱导的CACO3沉淀物的生长速率和特征的影响：粒子尺度的实验研究
Effects of bacterial density on growth rate and characteristics of microbial-induced CaCO3 precipitates: a particle-scale experimental study
论文作者
论文摘要
微生物诱导的碳酸盐沉淀（MICP）已被探索了十多年，作为一种有希望的土壤改善技术。但是，预测和控制CaCO3沉淀的生长速率和特征仍然有挑战性，这直接影响了经过MICP处理的土壤的工程性能。在这项研究中，我们采用基于微流体的孔尺度模型来观察细菌密度对在砂颗粒尺度上发生的MICP过程中CACO3沉淀的生长速率和特征的影响。结果表明，CACO3的降水速率随着细菌密度在0.6E8和5.2E8细胞/mL之间的范围内增加。细菌密度还会影响CACO3晶体的大小和数量。低细菌密度为0.6E8细胞/mL的平均晶体体积为8,000 UM3，而高细菌密度为5.2e8细胞/mL，产生了1.1E6晶体/mL，导致更多的晶体（2.0E7晶体/mL），但平均晶体体积较小，晶体较小450 UM3。当细菌密度为0.6E8细胞/mL时，产生的CACO3晶体是稳定的。当细菌密度高4-10倍时，晶体首先不稳定，然后转化为更稳定的CACO3晶体。这表明细菌密度在MICP方案的设计中应该是一个重要的考虑因素。
Microbial-Induced Carbonate Precipitation (MICP) has been explored for more than a decade as a promising soil improvement technique. However, it is still challenging to predict and control the growth rate and characteristics of CaCO3 precipitates, which directly affect the engineering performance of MICP-treated soils. In this study, we employ a microfluidics-based pore scale model to observe the effect of bacterial density on the growth rate and characteristics of CaCO3 precipitates during MICP processes occurring at the sand particle scale. Results show that the precipitation rate of CaCO3 increases with bacterial density in the range between 0.6e8 and 5.2e8 cells/ml. Bacterial density also affects both the size and number of CaCO3 crystals. A low bacterial density of 0.6e8 cells/ml produced 1.1e6 crystals/ml with an average crystal volume of 8,000 um3, whereas a high bacterial density of 5.2e8 cells/ml resulted in more crystals (2.0e7 crystals/ml) but with a smaller average crystal volume of 450 um3. The produced CaCO3 crystals were stable when the bacterial density was 0.6e8 cells/ml. When the bacterial density was 4-10 times higher, the crystals were first unstable and then transformed into more stable CaCO3 crystals. This suggests that bacterial density should be an important consideration in the design of MICP protocols.
