Jiangsu Key Laboratory of Construction Materials, Nanjing, 211189, China.
School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
J Environ Manage. 2022 Aug 15;316:115280. doi: 10.1016/j.jenvman.2022.115280. Epub 2022 May 16.
Microbial-induced struvite precipitation (MISP) is a new biocementation method for soil improvement and hydraulic permeability reduction. Compared with traditional microbial-induced carbonate precipitation (MICP), MISP can significantly reduce the production of harmful ammonium ions during biochemical reactions and convert ammonium ions into struvite with promising mechanical strength. In this study, a series of experiments were conducted to compare the performance of the MICP and the MISP processes on sandy soils. Results showed that the average content of calcium carbonate in MISP cemented sand columns after 3 times of injection is similar to that in MICP cemented sand columns after 9 times of injection. The hydraulic permeability of MISP cemented sand columns after 3 times of injection is an order of magnitude lower than that of MICP cemented sand columns after 9 times of injection. To further investigate the physicochemical interactions during MISP and MICP processes, a one-dimensional finite element code considering the chemical reactions and the solute transportation was proposed. Results show that most of the MISP were formed in the early 3 h of the 6 h injection cycle, whereas most of the MICP were formed in the last 5 h of the injection cycle. The simulated total mass of the MISP precipitation, 11.3 g, was close to the experimental result of 9.6 g. The spatial distribution of MISP is more uneven as compared to MICP, as a result of the much faster reaction rate of struvite than calcium carbonate. The findings suggested that MISP could partially replace MICP in the applications of leakage mitigation and reinforcement of sandy soils.
微生物诱导的鸟粪石沉淀（MISP）是一种用于改良土壤和降低水力传导性的新型生物胶结方法。与传统的微生物诱导碳酸钙沉淀（MICP）相比，MISP 可以在生化反应过程中显著减少有害氨离子的产生，并将氨离子转化为具有良好机械强度的鸟粪石。在这项研究中，进行了一系列实验来比较 MICP 和 MISP 工艺在砂质土中的性能。结果表明，经过 3 次注射后，MISP 胶结砂柱中的碳酸钙平均含量与经过 9 次注射后 MICP 胶结砂柱中的碳酸钙平均含量相似。经过 3 次注射后，MISP 胶结砂柱的水力传导性比经过 9 次注射后 MICP 胶结砂柱的水力传导性低一个数量级。为了进一步研究 MISP 和 MICP 过程中的物理化学相互作用，提出了一个考虑化学反应和溶质传输的一维有限元代码。结果表明，MISP 主要在 6 小时注射周期的前 3 小时形成，而 MICP 主要在注射周期的最后 5 小时形成。模拟的 MISP 沉淀总质量为 11.3g，与实验结果 9.6g 接近。与 MICP 相比，MISP 的沉淀空间分布更为不均匀，这是由于鸟粪石的反应速率比碳酸钙快得多。研究结果表明，MISP 可以在减少渗漏和加固砂质土等应用中部分替代 MICP。
