Factors Affecting the Kinetics of Urea Hydrolysis via Sporoscarcina pasteurii

Abstract

Microbial induced carbonate precipitation (MICP) is a bio-mediated approach to improve engineering properties of granular materials. Cell population, substrate concentration, alkalinity, and temperature are the main factors controlling urea hydrolysis rate in the MICP process. In this study, the effects of initial substrate (urea) concentration and cell population on the rate of urea hydrolysis were evaluated using electrical conductivity as a monitoring method. For this purpose, a correlation between electrical conductivity and hydrolyzed urea concentration was derived from a batch test program. Various initial substrate concentrations and cell populations were selected in another batch test program to evaluate their contribution to the urea hydrolysis rate. Increasing both initial substrate concentration and cell population accelerated the rate as discussed in detail in this paper. Finally, a simplified column testing program was completed to demonstrate the effectiveness of electrical conductivity as a monitoring parameter during MICP treatment.