Friendly cement, helpful bacteria

Green cements and low carbon cements have been on the anvil but now, a Stanford Professor has invented a new type of cement that is carbon neutral—a huge innovation for a material whose production process normally spews vast amounts of CO2 into the atmosphere.

But Novacem, a British spin-out, is attempting to make a cement that actually sequesters carbon. Low carbon cement is needed not only for buildings, but for also for binding together concrete freeway overpasses.

Novacem’s cement will actually absorb more carbon dioxide over its life cycle than it emits. Instead of using limestone; they make cement from magnesium silicates which don’t emit CO2 in manufacture but actually absorb carbon dioxide as they age.

In yet another promising find, a new desalination process will generate electricity as well as clean water, according to a team of researchers from the US and China.

The team uses a microbial fuel cell, which uses bacteria to convert wastewater into clean water and electricity, to desalinate salt water.

Instead of requiring an electrical input and high water pressure to desalinate water, the new process uses organic matter to remove 90% of salt from brackish water or seawater. Typical microbial fuel cells have two chambers – one containing wastewater or other nutrients and the other water – each fitted with an electrode. Bacteria in the wastewater consume the organic material, generating electricity in the process.

In the new process a third chamber containing seawater is added to the fuel cell in between the other chambers, separated by ion-specific membranes. When the bacteria consume the wastewater, charged ions are produced, which are separated by the membranes. Some are consumed at the electrodes – desalinating the water in the central chamber and generating a current.

Not yet a practical system, there is proof of concept, as the team says.

Bacteria are the original inhabitants of the planet, we have merely inherited the earth from them. No wonder they have a few tricks up their sleeve, which we are only beginning to understand. Bacteria is also being used to convert cellulose to biofuel.