Machine uses pee to create 'biological concrete'

A new portable machine uses a mixture of sand, bacteria and urine to create an eco-friendly concrete-like material that can be used to make bricks to build houses.
The machine, called 'Dupe', 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, 'Gizmag' reported.
Designer Peter Trimble, while studying at the Edinburgh College of Art, decided to look at the sustainability of material production and found that cement production was the most environmentally damaging.

He then developed the biostone which is environmentally-friendly, but can be easily made as bricks for building housing in developing countries or remote places.
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 process forms mineral composites at biological temperatures," said Trimble.
"The biomaterial is structurally comparable to concrete, yet the production of the biomaterial produces no greenhouse gases.
"Concrete is responsible for 5 per cent 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," Trimble said.