Microbial-induced calcite precipitation (MICP) is taking steps beyond the laboratory as researchers successfully scale the technique to 900-liter batches, providing viable solutions for sustainable construction.
Innovative methodologies leveraging the natural capabilities of ureolytic microorganisms hold promise for changing the future of building materials and geoengineering applications. A recent study, published by researchers from various institutions including support from the Swiss Innovation Agency, details the transition from laboratory results to practical application, addressing the real-world challenges faced by large-scale MICP processes.
The potential for MICP as a sustainable alternative to traditional binding agents is widely recognized. This biocementation technique utilizes microorganisms to produce calcium carbonate (CaCO3), which naturally binds soil particles together, creating strong structures without the environmental drawbacks associated with standard construction materials.
The researchers of the study scoured over 50 microbial strains, sourcing some from the fertile soils of Ticino, Switzerland, where environmental conditions encourage high urea production, alongside additional strains sourced from microbial banks and industrial bioreactors. Ureolytic bacteria function by breaking down urea, leading to the precipitation of calcium carbonate, thereby strengthening the soil.
The research revealed significant results during the cultivation of microorganisms. The team found their optimized cultivation methods could sustain the growth of the highly effective ureolytic strain, Sporosarcina pasteurii, without contamination across six sequential 900-liter bioreactor batches. The successful control of experimental conditions ensured the dominance of this strain, with others overpowered during the culturing process.
Highlighted by no signs of contamination, the study demonstrated the successful cultivation of the dominant bacterial cultures, producing enough biocementing agent to create architectural materials on the scale previously deemed impractical. Following these successful growth experiments, the culture was used to biocement a column made of fine sand measuring 1.5 meters tall.
These large-scale experiments revealed promising results: the biocemented sand column exhibited undrained Tresca strength values between 90 and 140 kPa. Such strength metrics signal the column's capacity to support weight and maintain integrity, enabling its integration without confinement, showcasing the immediate applicability of this research to geotechnical and building projects.
"The produced culture, obtained under optimized medium composition, was used to induce biocementation successfully," the authors indicated, emphasizing both the effectiveness and viability of scaling MICP practices for real-world implementation.
Overall, this study marks a pivotal advancement for MICP approaches, reinforcing the technique's potential for sustainable construction materials capable of decades of service without extensive environmental impact. Not only does this open doors for new applications, but it also encourages the exploration of untapped microbial sources to maximize efficiencies.
Future research avenues could focus on refining cultivation methods, enhancing ureolytic efficiencies, and exploring wider field applications, cementing MICP’s role as a cornerstone of green building practices. With continued inquiry, the possibilities for biocementation could reshape construction practices wholly, integrating ecological harmony with engineering innovation.