Effect of different biological solutions on microbially induced carbonate precipitation and reinforcement of sand

Abstract

Sporosarcina pasteurii is widely used in the application of microbially induced carbonate precipitation (MICP) for various applications, such as ground reinforcement, erosion mitigation or stabilization of sand foreshore slopes. This study focuses on the effect of thallus resuspended by the fresh medium (RF) on urea hydrolysis, MICP, and sand reinforcement compared with untreated biological solutions (US) with high microbial concentration. The principle is investigated by tests on thallus resuspended by saline solution [NaCl (0.9%)] (RS) and supernatant (SS). The results indicate that the addition of the fresh medium is insignificant for promoting MICP and even has a slightly negative effect on urea hydrolysis and sand improvement for stationary phase bacteria. The ability of US to hydrolyze urea and MICP is derived from two sources: urease existing in the cell bodies and free urease existing in solution for lysis of partial cells, with urease in cells accounting for the majority. The preferable sand reinforcement of US is primarily due to the high amount of carbonate precipitation and formation of non-biological calcium carbonate located primarily in the pores. The results indicate that the preference of US in various engineering applications with lower cost for the realizable reinforcement.

Keywords:

• Sand reinforcement
• microbially induced carbonate precipitation
• urease activity
• resuspension
• surface percolation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful for the technical and financial support Provided by National Key Research and Development Plan under Grant No. 2018YFC1505300-5.3 and 2016YFE0200100; and National Natural Sciences Foundation of China Granted No. 51639002; and State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China.