Dupe creates "biological concrete" from sand, bacteria and urine
By Stu Robarts
February 12, 2014
With energy production and raw material shortages becoming increasingly pertinent issues around the world, designer Peter Trimble has demonstrated a radical method of manufacture that addresses both issues. Dupe is a portable machine that uses a mixture of sand, bacteria and urine to create a material called biostone. The machine is a proof-of-concept design only and is currently set up to create a small stool, but the method can be adapted to create just about anything.
Trimble's work was part of an open brief while studying at the Edinburgh College of Art. He decided to look at the sustainability of material production and found that cement production was the most environmentally damaging. Not only is the biostone he subsequently produced environmentally-friendly, but it could be easily made as bricks for building housing in developing countries or remote places.
"Currently, materials use 'heat, beat and treat' methods of production, carving things down from the top with 96 percent waste and only 4 percent product," says Trimble. "The 96 percent can be accounted for through the mining of raw materials, the burning of fossil fuels in manufacture and transportation at each stage of the products life."
The procedure for creating biostone involves filling a mold of the final required shape with sand before pumping a bacteria solution of bascillus pasterurii (which has been grown in a nutrient broth) into the mold and leaving the mixture to establish itself overnight. A solution of calcium chloride, urea and nutrient broth is then pumped into the mold. The bacteria uses the urea as energy to absorb the calcium chloride and convert it into calcium carbonate, a cement-like mixture that binds the sand together within the mold.
"The development process was difficult, particularly getting the recipe for the chemicals correct," explains Trimble to Gizmag. "I had lots of problems with PH levels. At the beginning the solution would kill the bacteria or cause the calcite to precipitate too quickly. I found that pumping the solution upwards (against gravity) through the sand produced more consistent results as it avoided preferential flow. Other problems where fundamental things like the molds leaking."
According to Trimble, the method of "microbial manufacture" used by Dupe explores the possibility of replacing energy-intensive methods of production with more efficient, biological processes. Though not aiming to provide any definitive answers, he hopes the project will encourage discussion about how industrial manufacturing can be made more sustainable.
"The process forms mineral composites at biological temperatures," says Trimble. "The biomaterial is structurally comparable to concrete, yet the production of the biomaterial produces no greenhouse gases. Concrete is responsible for 5 percent of the world's man-made CO2 emissions. The biomaterial produced by this process is a stepping stone in the right direction for the reduction of these carbon emissions."
Dupe is by no means the first time urine has been used for good. French design group Faltazi created L'Uritonnoir, a composting urinal that helps to turn a hay bales into fertilizer, and scientists at Bristol Robotics Laboratory created a urine-powered fuel-cell for mobile phones.
The video below shows the production process.
Source: Peter Trimble