Abstract
Microbially induced mineral precipitation is recognized as a widespread phenomenon in nature. A diverse range of minerals including carbonate, sulphides, silicates, and phosphates can be produced through biomineralization. Calcium carbonate (CaCO3) is one of the most common substances used in various industries and is mostly extracted by mining. In recent years, production of CaCO3 by bacteria has drawn much attention because it is an environmentally- and health-friendly pathway. Although CaCO3 can be produced by some genera of bacteria through autotrophic and heterotrophic pathways, the possibility of producing CaCO3 in different environmental conditions has remained a challenge to determine. In this study, calcium alginate was proposed as a protective carrier to increase the bacterial tolerance to extreme environmental conditions. The model showed that the highest concentration of CaCO3 is achieved when the bacterial cells are immobilized in the calcium alginate beads fabricated using 1.38% w/v Na-alginate and 0.13 M CaCl2.
Highlights
Calcium carbonate (CaCO3 ) comprises more than 4% of the earth’s crust
Induced CaCO3 precipitation has been successfully used for a wide range of applications including strengthening of sand and soil [1,2,3,4], removal of metal contaminants from the soil and groundwater [5], removal of calcium ions and polychlorinated biphenyls [6], remediation of monuments [7], CO2 sequestration [8], bio-deposition on porous mAterials such as limestone and brick [9,10], and, more recently, durability improvement of cementitious mAterials such as concrete [11,12,13]
Immobilization of bacteria cells can be achieved through four mAin categories, namely: (1) attachment or adsorption onto solid carrier surfaces; (2) entrapment within a porous mAtrix; (3) self-aggregation by flocculation or with crosslinking agents; and (4) cell containment behind barriers [22]
Summary
Calcium carbonate (CaCO3 ) comprises more than 4% of the earth’s crust It can be found throughout the world in natural forms such as mArble and limestone. Induced CaCO3 precipitation has been successfully used for a wide range of applications including strengthening of sand and soil [1,2,3,4], removal of metal contaminants from the soil and groundwater [5], removal of calcium ions and polychlorinated biphenyls [6], remediation of monuments [7], CO2 sequestration [8], bio-deposition on porous mAterials such as limestone and brick [9,10], and, more recently, durability improvement of cementitious mAterials such as concrete [11,12,13]
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