Towards the sustainable fine control of microbially induced calcium carbonate precipitation

Microbially induced calcium carbonate precipitation (MICP) has been proposed as a potential solution to address many environmental and engineering issues. However, how to quantitatively and accurately control this novel biological cementation technology is still a major challenge. This study designed a factorial test, a verification test and an application test to provide theoretical basis for fine control of MICP. We have systematically monitored and analyzed the changes of proteins and polysaccharide, pH, electrical conductivity (EC), and zeta potential of the precipitation environment, and tracked the particle size distribution and microstructures of bio-cements from beginning to end. Based on the laboratory investigations, we discovered the particle size of the precipitations showed distinct features based on the analysis of physicochemical indicators, and a model for fine control of particle size of bio-cements was proposed. Further, the validation test was completed by "factory on a chip" technology. We successfully realized the production of pre designed particle sizes, the robustness of our model and the mechanism of particle formation were verified. Finally, we designed a three-stage cementation strategy for the application test of bio-cement bonded glass beads columns. The fine control cementation strategy has a higher utilization rate of raw materials and can provide twice the cementation strength compared with the reference test. The results show that our proposed model makes an important step forward in the direction of optimized application of bio-cements, which may be used as a process control standard to promote environment -friendly and sustainable MICP.