Microbially induced carbonate precipitation has gained much attention recently as a more sustainable and ecofriendly approach. MICP is a geo-biochemical process which is catalyzed by urease. Urease hydrolyzes urea to produce carbonate ions, which leads to calcium carbonate formation in the presence of calcium ions. Formed calcium carbonate would work as a cementing material for soil stabilization. In this study, poly-L-lysine was used as an organic additive to accelerate the efficiency of MICP process. Poly-L-lysine is a cationic poly peptide around pH.7. Effects of poly-L-lysine on CaCO3 crystallization and soil stabilization were investigated in MICP catalyzed by Pararhodobacter sp. CaCO3 was precipitated with and without poly-L-lysine by hydrolysis of the urea by using Pararhodobacter sp. in the presence of CaCl2. By adding poly-L-lysine, larger amount of precipitate could be obtained than the conventional MICP method. Polymorphism and the morphology of the CaCO3 crystals were investigated by using the X-ray diffraction and scanning electron microscope. Twin sphere shaped calcite crystals were dominant with poly-L-lysine while rhombohedral shaped calcite crystals were obtained without poly-L-lysine. In addition, influence of the poly-L-lysine on sand solidification was investigated. Strongly cemented sand specimen with higher unconfined compressive strength (UCS) could be obtained by incorporating poly-L-lysine by forming adequate amount of bridge between the sand particles than the conventional MICP method (Figure 1). These results indicated that introducing poly-L-lysine is a more sustainable and environmental friendly way to increase the efficiency of MICP process.

Microbially induced carbonate precipitation assisted by poly-L-lysine: Ecofriendly approach inspired by nature

2019 Fall National Meeting

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