Insight into the influence of pH on the precipitation induced by bacteria

Abstract In recent years, microbial mineralization has aroused great attention in soil remediation. The pH is one of the critical factors that control the microbial mineralization process. However, the interaction mechanism between the environment pH and the mineralization process has not been clarified yet. This paper focused on the growth of bacteria, urease activity and the calcium utilization rate. Besides, we detected the particle size distribution, morphological characteristics and the composition of precipitations formed at different pH. Moreover, we evaluated the triaxial compressive strength of sand columns processed by different pH consolidation solutions. Additionally, the volume fraction of precipitations and its spatial distribution in sand columns were analysed by X‐ray CT. The results demonstrated that pH significantly influences the growth of bacteria and urease activity, especially in the bacteria's early growth stage. This paper also indicates that the environmental pH impacts the volume fraction of precipitations, affecting the consolidation properties. We also found a negative correlation between the cohesion and the total volume fraction of precipitations. In contrast, there was a positive correlation between the friction angle and the total volume fraction of precipitations. Moreover, we observed that the precipitations mainly distributed in the pores and throats, increasing the sand particles’ roughness. Furthermore, we proposed four cementing models for the spatial relationship between the precipitations and the sand particles, which provides new insight into the consolidation mechanism. This paper guides us to promote this environmentally friendly technology to treat soil liquefaction and desertification.