Inhibited and Retarded Behavior by Ca²⁺ and Ca²⁺/OD Loading Rate on Ureolytic Bacteria in MICP Process

Area of Science:

• Biogeochemistry
• Materials Science
• Microbial Engineering

Background:

• Estimating optical density (OD) for viable cells in engineering applications presents challenges.
• Microbially induced carbonate precipitation (MICP) is a key process influenced by environmental factors.

Purpose of the Study:

• To investigate the inhibitory and retarding effects of high Ca²⁺ concentrations on MICP.
• To determine the critical Ca²⁺/OD ratio that triggers inhibition.
• To establish a basis for designing MICP material blends without risk of inhibition.

Main Methods:

• Utilized OD conversion from a previous study.
• Examined the behavior of MICP under varying Ca²⁺ conditions.
• Analyzed the relationship between Ca²⁺ loading, OD, and carbonate precipitation rate (CPR).

Main Results:

• High Ca²⁺ concentrations were found to significantly inhibit and retard MICP processes.
• Inhibition and retardation effects were observed when the Ca²⁺/OD loading rate surpassed 8.46 M.
• A critical value of 8.46 M was identified as the proportional constant relating CPR to OD.

Conclusions:

• The inhibition and retardation of MICP are governed by Ca²⁺ load and a linear standard line (LSL).
• Cellular capacity or tolerance, represented by CPR/OD = 8.46 M or Ca²⁺/OD = 8.46 M, dictates these effects.
• Understanding these parameters allows for the safe and effective blending of materials for MICP applications.