IIT Madras researchers develop math model for understanding ‘bio-cement’

Researchers from the Indian Institute of Technology Madras have developed a structured model to help in the production of bio-cement, which is an alternative sustainable process for cementation. It has the potential to reduce the production of carbondioxide (CO₂) in the future.

Called ‘Microbially Induced Calcite Precipitation (MICP), this process is used to make bio-cement using bacteria. The research was focused to gain a better understanding of the MICP process with a long-term aim to scale up the manufacturing of Bio-Cement.

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Cement manufacturing is among the largest CO₂-producing industries. It is vital to develop alternative sustainable processes for manufacturing cement to reduce CO₂ emissions and bio-cement can be a major step in this direction.

The IIT Madras research team was led by Prof GK Suraishkumar, Department of Biotechnology; Nirav Bhatt, Assistant Professor, Department of Biotechnology; and Subasree Sridhar, Research Scholar, IIT Madras. The findings of their research were published in the reputed peer-reviewed Biochemical Engineering Journal.

The researchers studied the MICP process using the bacteria, S. pasteurii, and proposed and developed a structured model for the overall ureolysis processes (uptake and breaking of urea using bacteria) to scale up the MICP process.

Practical application

Explaining the applications of this research, Suraishkumar said, “The current applications are self-healing cement for sealing cracks in difficult-to-reach locations, consolidation of soil structures, removal of heavy metals and ‘radionuclides’ from drinking water, among others.”

He added, “A better understanding of the fundamental microbial processes such as overall ureolysis in the bio-cement formation could help us design and operate bioreactors for bio-cement production in the future to replace conventional cement for some applications.”

Further, highlighting the impact of this research, Suraishkumar, said, “In the short term, the better understanding would help us provide optimal conditions for effective self-healing cement applications, and soil consolidation, among other applications. In the long term, the better understanding would help produce conventional cement equivalent through a bio-route.”

MICP explained

Microbially Induced Calcite Precipitation (MICP) is the process by which calcium carbonate precipitates are formed by microorganisms, which are used to produce bio-cement. The developed structured model is useful for developing a unified model of ureolysis processes with calcite precipitation and MICP scale-up studies in the future.

Speaking on the current status of this research, Bhatt, , said, “MICP processes are currently modelled using unstructured models. Structured models of MICP provide better mechanistic insights into the bio-cementation process. Further, these models will be used in improving the process, rational process scale-up, and optimisation in the future.”

Why bio-cement

Bio-cement synthesis is more energy efficient as it requires temperatures in the range of 30° to 40°C whereas conventional cement production requires above 900⁰C. It is also eco-friendly with negligible carbondioxide emissions.

Bio-cement production can also be potentially more economical since production is faster and industrial wastes such as lactose mother liquor (LML) and corn steep liquor (CSL) can also be used as raw materials for the bacteria. Research on bio-cement has shown that it has comparable shear strength, durability, reduced water absorption capacity, and permeability to the conventional cement.

In the future, the process of bio-cement production is likely to be significantly different from the current process in a cement factory. The production is likely to be at the place of use, on a need basis, by relevant micro-organisms. There may not be a need to transport dry cement powder and mix it with sand, both of which are unsustainable in the long run.

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