Abstract
SummaryThis paper presents a novel approach of using in‐situ microbially induced Ca2+‐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 Ca2+ 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 CaCO 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 Cu2+ 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.
Highlights
It has been well recognized that seepage flow has a great influence on the stability of geotechnical structures and the safety of environment
To overcome the aforementioned disadvantages, the current study presents a new method for soil hydraulic conductivity reduction and seepage control by injection of low viscous alginate solution followed by an in-situ slow and controllable gelation process
This study has clearly demonstrated that it is feasible to use this method for seepage control in soils and copper ion removal
Summary
It has been well recognized that seepage flow has a great influence on the stability of geotechnical structures and the safety of environment. Various solutions have been proposed for seepage control, e.g. cement grouting, chemical grouting, or slurry cut-off walls (Xanthakos et al, 1994; Chu et al, 2009). One common method for seepage control is to change the internal hydraulic properties of the materials, such as the permeability of sand by injection of sealant such as cement, chemicals or polymers (e.g. polyurethane prepolymer) into the pores of the porous materials to stop water seepage (Chen et al, 2010; Lisa et al, 2013; Lentz, 2015). It is difficult to inject viscous sealant such as cement or polymers into soil. There is environmental concern related to the unrecoverable change of the natural soil due to the injection of cement or chemical grouts (Farah et al, 2016)
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