In‐situ microbially induced Ca²⁺‐alginate polymeric sealant for seepage control in porous materials

Abstract

Summary This paper presents a novel approach of using in‐situ microbially induced Ca 2+ ‐alginate polymeric sealant for seepage control in porous materials. This process comprises two steps: (i) generation of insoluble calcium carbonate inside the pores of porous materials (such as sand) through a microbially induced carbonate precipitation ( MICP ) process in‐situ and (ii) injection of sodium alginate for in‐situ gelation via reaction between alginate and Ca 2+ ions. The experimental results showed that the hydraulic conductivity/permeability of sand decreased with the increase in alginate concentration. When 5% alginate was used with a Ca CO 3 concentration of 0.18 g g −1 sand, the permeability of the alginate‐treated sand reduced from 5.0 × 10 −4 to 2.2 × 10 −9 m s −1 . The scanning electron microscopy images revealed that a film‐type coating was formed around sand particles with spherical round crystals embedded. Furthermore, the in‐situ formed Ca‐alginate polymeric sealant can also be used for the removal of Cu 2+ ion and suspended particles from contaminated water by more than 90%. Built on the current research, the envisioned practical application of the proposed method may include clogging fractured rock, reducing seepage and prevent piping through dams, excavation dewatering, and forming barriers for remediating specific contaminants.

Environmental geotechnics: challenges and opportunities in the post-Covid-19 world

“…However, the use of bacteria for experimental purposes in actual in-situ conditions can be sensitive. Alternatively, enzymes can be used instead, and enzyme or polymer-based methods have also been developed in recent years (Khatami and O'Kelly, 2013;Cheng et al 2019;He et al 2020).…”

Geotechnical Engineering Properties of Soils Solidified by Microbially Induced CaCO3 Precipitation (MICP)

“…e test results showed that the construction process can effectively reduce the permeability coefficient of the sand surface and thus meet the engineering requirements. Cheng et al [121] applied CaCO 3 precipitation techniques combined with the reaction of sodium alginate with Ca 2+ ions to form a gel-like calcium alginate for sand seepage control treatment. e test results showed that the permeability of the treated sand decreased from 5.0 × 10 −4 m/s to 2.2 × 10 −9 m/s and that the seepage control efficiency increased by one to two orders of magnitude compared to that treated with pure MICP technology.…”

Recent development in biogeotechnology and its engineering applications

“…1, stiffness [115,118,[123][124][125][126][127][128][129][130][131][132], and thermal conductivity [133,134], etc. Some studies also proposed to further enhance the strength of bio-cemented soil by adding other materials, such as lime [42], fiber [54,125,[135][136][137][138][139][140][141][142][143], hydrogelassisted [144], the hydrophilic polymer [145,146], and alginate [147]. MICP based soil improvement involves a highly complex biological, physical and chemical process, which is mainly affected by the following four aspect factors: 1) soil properties, 2) urease producing bacteria (UPB) characteristics, 3) cementation solution (CS) parameters, and 4) treatment process.…”

“…Cementation solution (CS) is usually a mixture of calcium and urea. Some other substances may also be added to the CS in some studies, such as nutrient broth, NH 4 Cl and NaHCO 3 [14,38,123,146,152,155,157,199,206,[212][213][214][215][216][217], yeast extract [31,184], Tris base [31], sodium malate [38], sodium acetate [48,184], and polyvinyl alcohol [146]. Chen et al [218] also proposed to use urine as the urea source for MICP treatment.…”