Bioprecipitation of calcium carbonate mediated by ureolysis: A review

Abstract

Ureolysis-driven microbially induced carbonate precipitation (MICP) is a naturally occurring process facilitated through microbial activities and biogeochemical reactions to produce calcium carbonate (CaCO3) mineral. MICP serves as an alternative ground improvement binder method to conventional technologies which is sustainable, requires low energy for its treatment process, results in a minimal carbon footprint and could offer economic benefits. In the last two decades, MICP has drawn great interest from the scientific community because of its practicality to stabilize granular soils, repair concrete cracks and remediate heavy metals. To obtain successful MICP application, it is vital to understand the conditions that favor its process. This paper, therefore, provides an overview of literature on CaCO3 precipitation mediated by ureolysis-driven MICP and its mechanism. The review includes a discussion on sources of urease enzyme from microorganisms used to induce CaCO3 crystal formation required for implementation of MCIP for ground improvement. Moreover, the key factors that influence the outcome of MICP and bio-engineering testing methods typically used to evaluate MICP performance are also highlighted. Finally, this review also provides insight on the current drawbacks (i.e. ammonium production, scale-up bioprocess and treatment cost) affecting MICP technology and recommendations for future consideration.