Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

ABSTRACTMicrobially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate byMethylocystis parvusOBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation,M. parvuswas incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3g of Ca(CHOOH)2−1calcium carbonate precipitate yield was obtained when a culture of 109cells ml−1and 5 g of calcium formate liter−1were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry.