Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-Ku, Sapporo, 060-8628, Japan.
Department of Engineering Technology, Faculty of Technology, University of Jaffna, Kilinochchi, 44000, Sri Lanka.
Environ Sci Pollut Res Int. 2023 Feb;30(6):15230-15240. doi: 10.1007/s11356-022-23157-8. Epub 2022 Sep 27.
Microbial induced carbonate precipitation (MICP) is one of the most commonly researched topics on biocementation, which achieves cementation of soil particles by carbonate from urea hydrolysis catalyzed by microbial urease. Although most MICP studies are limited to stabilizing sandy soils, more researchers are now turning their interest to other weak soils, particularly organic soils. To stabilize organic soils, the influence of humic substances should be investigated since it has been reported to inhibit urease activity and disrupt the formation of calcium carbonate. This study investigates the effect of humic acid (HA), one fraction of humic substances, on MICP. For this purpose, the effects of HA content on CaCO precipitation using three strains and on CaCO morphology were examined. The results showed that native species in organic soils were less adversely affected by HA addition than the exogenous one. Another interesting finding is that bacteria seem to have strategies to cope with harsh conditions with HA. Observation of CaCO morphology revealed that the crystallization process was hindered by HA to some extent, producing lots of fine amorphous precipitates and large aggregated CaCO. Overall, this study could provide an insightful understanding of possible obstacles when using MICP to stabilize organic soils.
微生物诱导碳酸钙沉淀（MICP）是生物胶结中研究最多的课题之一，它通过微生物脲酶催化尿素水解产生的碳酸盐来实现土壤颗粒的胶结。尽管大多数 MICP 研究仅限于稳定砂质土壤，但现在越来越多的研究人员将兴趣转向其他弱土壤，特别是有机土壤。为了稳定有机土壤，应该研究腐殖质的影响，因为已有报道称腐殖质会抑制脲酶活性并破坏碳酸钙的形成。本研究调查了腐殖酸（HA）作为腐殖质的一种对 MICP 的影响。为此，研究了 HA 含量对三种菌株的 CaCO3 沉淀和 CaCO3 形态的影响。结果表明，与外源菌相比，有机土壤中的本土菌受 HA 添加的影响较小。另一个有趣的发现是，细菌似乎有应对 HA 等恶劣条件的策略。对 CaCO3 形态的观察表明，HA 在一定程度上阻碍了结晶过程，产生了大量细小的无定形沉淀物和大的聚集 CaCO3。总的来说，这项研究可以深入了解在使用 MICP 稳定有机土壤时可能遇到的障碍。
