Study on the electrokinetic effect of the microbially induced calcium carbonate precipitation process using integrated electric-microfluidics

Microbially induced calcium carbonate precipitation(MICP) represents a promising and innovative soil improvement technology. To address the challenges associated with large-scale in situ bio-mediated soil improvement, electrokinetic technology is proposed to regulate the MICP process. This study explores the electrokinetic effects of the biomineralization process using integrated electric-microfluidics. The migration of bacteria and precipitation of calcium carbonate crystals were analyzed to understand the influence of direct current(DC) electric fields on bacterial and calcium carbonate distribution. Calcium carbonate precipitation patterns in a porous medium were compared under electric fields of different orientations to identify key mechanisms in electrically regulated microbial-induced calcium carbonate precipitation. Experimental results indicate that the applied DC electric field induced bacterial migration towards the anode. Furthermore, under the applied DC electric field, the primary calcium carbonate precipitation area shifted from the middle of the porous medium,where the bacterial and cementation solutions met, to areas in the middle of the chip and near the cathode. Consistently, calcium carbonate precipitated preferentially near the cathode regardless of the electric field direction, suggesting that calcium ion migration driven by the electric field is the potential mechanism controlling calcium carbonate distribution. This study provides new insights into the potential application of electrokinetic technology for bio-mediated soil improvement.