Abstract

In recent years, microbially induced calcite precipitation (MICP) process has attracted great interest. Calcite precipitation can be induced by different microorganisms as a result of different metabolisms, being ureolytic MCP the most common alternative. One of the great disadvantages of ureolytic MICP is the release of ammonia to the environment. Calcite precipitation may also be induced through the uptake of inorganic carbon by autotrophic microorganisms, such as microalgae and cyanobacteria. In this case no urea hydrolysis is required, so no release of urea is linked to calcite precipitation. This research evaluated the behaviour of photosynthetic MICP, using the cyanobacterium Anabaena variabilis. In particular, the influence of photosynthetic activity, calcium and inorganic carbon available on precipitation yield and crystal morphology was evaluated. The results shows that cyanobacteria play a role promoting the nucleation sites and inducing an alkaline environment for CaCO3 precipitation. Furthermore, the results show that a decrease in the average light intensity increases the CaCO3 precipitation yield. Finally, the precipitates morphological analysis showed that the photosynthetic activity and the presence of the microorganism plays a relevant role in the formation of more complex microcrystalline structures (such as rods, pseudododecahedra and rosette-like appearance), which can be obtained in a controlled way by setting specific light and calcium conditions. Thus, under tested conditions, the cyanobacterium Anabaena variabilis can promote CaCO3 precipitation, which makes it a good candidate for photosynthetic MICP. © 2024 Elsevier B.V.