矿化水环境下微生物耐盐度驯化及MICP固化沙漠沙试验研究

    Experimental study on microbial salinity domestication and MICP-treated desert sand in mineralized water environment

    • 摘要: 为突破沙漠地区淡水资源匮乏与运输成本高的工程限制,提出以矿化水代替淡水的微生物固沙技术。通过微生物耐盐度驯化和培养,结合碳酸盐沉淀微观分析及固沙试验,研究矿化水环境下微生物矿化机理及其固沙效果。结果表明:微生物的耐盐度驯化可使其逐步适应矿化水环境,并且驯化后单位细菌的矿化效率亦得到提高;矿化水对细菌的增殖及脲酶的分泌量具有抑制作用,但脲酶比活力随矿化度的提升呈现正向响应;去离子水环境下碳酸盐晶体以六棱柱形方解石为主,而矿化水环境下以三棱锥形方解石、镁-方解石与球形球霰石的包覆式复合结构为主,且随着矿化度的提高晶体尺寸减小。通过固沙试验发现矿化水环境下固沙效果弱于去离子水环境,但两者的钙离子转化率均在配合比2:1时超过了90%;当配合比2:1,胶结液浓度≥1.5 mol/L时,经过三轮固化可抵御10 m/s的风力侵蚀。总之,适当增加固化轮次可有效补偿矿化水抑菌效应,实现较好的抗风蚀效果。

       

      Abstract: To overcome engineering constraints posed by scarce freshwater resources and high transportation costs in desert regions, a microbial sand fixation technology using mineralized water instead of fresh water was proposed. The biomineralization mechanism and sand-fixing efficacy in a mineralized water environment were studied by microbial salinity domestication and culture, combined with microscopic analysis of carbonate precipitation and sand-fixing tests. The results showed that microorganisms gradually adapt to the mineralized water environment through salinity acclimation, and individual bacterial mineralization efficiency was also improved. Bacterial proliferation and urease secretion were inhibited by mineralized water, but urease-specific activity showed a positive response to increasing salinity. In deionized water, carbonate crystals were mainly hexagonal prismatic calcite, whereas in mineralized water, they were mainly coated structures composed of triangular-pyramidal calcite, Mg-calcite, and spherical vaterite, with crystal size decreasing as salinity increased. Sand fixation experiments reveal that the solidification effect in mineralized water environments is weaker than that in deionized water. Still, the calcium ion conversion rate exceeded 90% in both environments when the mixture ratio was 2:1. The MICP-treated samples with three treatment cycles could resist wind erosion at 10 m/s when the mixture ratio was 2:1, and the cementation solution concentration was ≥ 1.5 mol/L. In summary, increasing treatment cycles effectively mitigates the bacteriostatic effect of mineralized water, leading to improved wind erosion resistance.

       

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