Impact of bacteria and urease concentration on precipitation kinetics and crystal morphology of calcium carbonate

摘要

Microbial/Enzyme-induced carbonate precipitation uses bacteria/urease to drive the biogeochemical reactions to generate CaCO3 precipitation. The goal of this study was to assess the impact of initial concentrations of urease and bacteria on precipitation kinetics and crystal morphology (crystal shape and chemical composition) of calcium carbonate precipitation. Experimental results showed that the CaCO3 precipitation kinetics were well-fitted by a modified exponential logistic model with a confidence value of 95%, and higher concentrations of bacteria and urease could increase the precipitation rate of CaCO3. The results of XRD, FTIR and SEM indicated that vaterite phase was the dominant form of CaCO3 crystals in bacteria-induced system, and calcite phase was the primary form of the CaCO3 crystals in urease-induced system. The results also showed that the effect of initial concentrations of bacteria and urease on the morphology of CaCO3 crystals was insignificant.