Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

Abstract

e Microbially 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 by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was 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 CaCO 3 g of Ca(CHOOH) 2 ؊1 calcium carbonate precipitate yield was obtained when a culture of 10 9 cells ml ؊1 and 5 g of calcium formate liter ؊1 were 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. Microbially induced carbonate precipitation (MICP) is a wellknown process and has been extensively described in the past (1-3). In short, MICP produces carbonate minerals, e.g., calcium carbonate, as a result of alterations in environmental conditions. In nature, examples of MICP include calcite formation in soils (4), limestone caves (5), seas (6), and soda lakes (7). Four different key parameters that govern microbially induced calcium carbonate precipitation are the: (i) concentration of nonprecipitated calcium, (ii) concentration of the total inorganic carbon, (iii) pH, and (iv) availability of nucleation sites for calcium carbonate crystal formation (3). Among the four parameters, bacterial activities mainly influence the pH of the environment (1).MICP is the basis for several biotechnological applications in the construction sector (for a review, see reference 1 and references therein). These include the use of calcium carbonate precipitate to protect concrete surface against the ingress of deleterious substances (e.g., chloride ions) (8) or to heal cracks in aging concrete (9, 10). Among the bacterial activities that can induce calcium carbonate precipitation, urea degradation by heterotrophic bacteria is typically used for applications on building materials. In biogenic urea degradation, urea is transformed to ammonia and carbonate ions to initiate precipitation (11). Bacillus spp. (e.g., B. sphaericus) is the most commonly applied urea degrader for MICP in the construction sector due to several advantages such as the high initial urea degradation rate by the strain and a highly negative potential ...

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Mineral formation during bacterial sulfate reduction in the presence of different electron donors and carbon sources

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Biogenic concrete protection driven by the formate oxidation by Methylocystis parvus OBBP

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