Spatiotemporal evolution of microbial-induced calcium carbonate precipitation based on microfluidics

The microbial-induced calcium carbonate precipitation (MICP) is a hot research topic in recent years, however, the understanding of its spatiotemporal evolution is still insufficient. This paper aims to investigate the spatiotemporal evolution process by designing a conceptual microfluidic chip within large and small pores and using a visualized experimental platform. An image-processing method is proposed to distinguish the calcium carbonate and measure its areas during the precipitation process, which allows the quantitative study on the spatiotemporal evolution process of MICP. The results show that the pore structures are involved in regulation of crystallization of the calcium carbonate. The calcium carbonate in the large pores of the channel exhibit as a single crystal, while those in the small pores between the sand particles show asymptotic growth in the form of aggregates and exhibit three different growth processes. Regardless of single crystal or crystalline aggregates, the growth rate of the calcium carbonate first increases and then gradually decreases with the increasing reaction time. The maximum growth rate is 4.22 μm/min with respect of the equivalent radius of the calcium carbonate crystals. This study is expected to benchmark the pore-scale modeling of biomineralization and provide reference for field practices.