Facilitation of microbially induced calcite precipitation with kaolinite nucleation

Microbially induced calcite precipitation is an emerging environmentally friendly ground improvement technique for a range of geotechnical applications. One of the remaining issues for field implementation of this technique is poor uniformity of calcite, with concentrated precipitation near the injection point, particularly for treatments with continuous injection or in fine sand. Therefore, the work described in this paper performed an experimental investigation to test the hypothesis that using kaolinite particles can increase the number of calcite nucleation sites throughout the sand medium to increase the mass of calcite deposited and provide better distribution of calcite. Both batch and column tests were performed to quantify the impact of kaolinite particles on calcite precipitation. The results indicated that the kaolinite particles may play a role as nucleation sites and facilitate the heterogeneous nucleation of calcite, with observed deposition profiles of kaolinite and breakthrough curves of both kaolinite and bacteria demonstrating that the uniform distribution of deposited kaolinite particles at relatively low inlet concentration (100 mg/l) most effectively increased the amount of calcite, producing a uniform calcite deposition profile. In addition, the results also showed that the well-predicted deposition profile of kaolinite correlated well with the deposited calcite profile.