Towards a low CO2 emission building material employing bacterial metabolism (1/2): The bacterial system and prototype production

Abstract

The production of concrete for construction purposes is a major source of anthropogenic CO 2 emissions. One promising avenue towards a more sustainable construction industry is to make use of naturally occurring mineral-microbe interactions, such as microbial-induced carbonate precipitation (MICP), to produce solid materials. In this paper, we present a new process where calcium carbonate in the form of powdered limestone is transformed to a binder material (termed BioZEment) through microbial dissolution and recrystallization. For the dissolution step, a suitable bacterial strain, closely related to Bacillus pumilus , was isolated from soil near a limestone quarry. We show that this strain produces organic acids from glucose, inducing the dissolution of calcium carbonate in an aqueous slurry of powdered limestone. In the second step, the dissolved limestone solution is used as the calcium source for MICP in sand packed syringe moulds. The amounts of acid produced and calcium carbonate dissolved are shown to depend on the amount of available oxygen as well as the degree of mixing. Precipitation is induced through the pH increase caused by the hydrolysis of urea, mediated by the enzyme urease, which is produced in situ by the bacterium Sporosarcina pasteurii DSM33. The degree of successful consolidation of sand by BioZEment was found to depend on both the amount of urea and the amount of glucose available in the dissolution reaction.

A sample cell for the study of enzyme-induced carbonate precipitation at the grain-scale and its implications for biocementation

“…Dissolved chalk solution (DCS) was produced as described previously 22 , and used as a cost-effective calcium source for EICP 13 . Usually, is used in EICP/MICP, however, chloride-ions react fast to form chloride salts and pollute water and can lead to steel corrosion of steel-reinforcement in concrete.…”

“…In the production of a biocemented material, several injections of the crystallization solution are often needed in order to achieve sufficient consolidation of the granular material 13 – 16 . For the first injection in EICP, mainly the sand needs to be considered as nucleation surfaces for heterogeneous nucleation.…”

Critical Review of Solidification of Sandy Soil by Microbially Induced Carbonate Precipitation (MICP)

“…In recent years, researchers have proposed substitutes for commonly-used calcium salts, such as eggshells, seawater, papermaking wastewater, which are more economical and environmentally friendly [150]. Røyne et al [151] proposed the use of limestone powder as the calcium source for MICP application. First, the limestone powder was dissolved by bacteria AP-004 screened and analyzed from soil near the quarry, and then urease-catalyzed urea hydrolysis was induced by Sporosarcina pasteurii to develop an adhesive, providing a new idea for the source of calcium salt.…”

Opportunities and challenges for engineering construction materials as carbon sinks

“…For bio-cements, depending on the application and production method, emissions could be higher than conventional cement [63]. While there has been recent progress in understanding the relationship between input feedstocks for biomineralization and material performance [64], large variability in performance remains [53,64,65].…”