Waterkiln

submerged soft cast MICP biofabrication

Research and Fabrication Team: Crystal Wang, Thora H Arnardottir, Jamie Haystead, Soley Eiriksdottir, Meng Zhang & Martyn Dade-Robertson

The Water Kilin Project Uses Submerged Fabric Casts and Natural Bacterial Processes
to Transform Sand into Sustainable Architectural Structures.

The Water Kiln project represents a fabrication approach, focusing on the use of submerged soft fabric cast to mineralise aggregates, such as sand, through a biological process. This approach utilises the natural biomineralisation capabilities of Sporosarcina pasteurii bacteria, by employing Microbiologically Induced Calcium Carbonate Precipitation (MICP) to create sustainable and architecturally applicable forms. By inoculating these bacteria into a fabric cast filled with sand and liquid medium and submerging them in a cementation medium, the process triggers the formation of calcium carbonate crystals entirely underwater, naturally cementing the sand particles into solid elements. 

The key to this process is maintaining a controlled environment for the moulds to go into that optimises the biomineralisation process, ensuring uniform material hardening. The potential for scalability and architectural applications is demonstrated through the design of a prototype column.

Building on previous MICP applications, this research investigates a soft casting technique using fabric mesh and acrylic scaffolds, aimed at enhancing the efficiency of biomineralisation in submerged environments. The methodology employed involves dissolving calcium ions and urea, with the latter enzymatically hydrolysed by the bacteria to form CaCO₃, acting as a binder for the particulate matter. The experimentation led to the development of bioreactors, termed “Water Kilns,” which mimic traditional kilning processes using a biotic liquid medium to solidify sand aggregates. Various experimental setups were tested to identify optimal conditions for maximising the biomineralisation efficiency.

Results from this exploration revealed patterns in calcium ion utilisation and the impact of different experimental conditions on the formation of CaCO₃ crust to act as a glazing method. The findings suggest the effectiveness of certain concentrations of the cementation solution, the role of nutrient broth, and the frequency of medium changes in enhancing biomineralisation outcomes. Improvements in the process of forming the biomineralised panels indicate areas for future research, particularly in reducing crust formation for easier extraction and optimisation of chemical usage for greater efficiency.

Water Kiln is a project from the Living Construction Group, 2024.