We could make fuel and fertiliser by recycling wastewater

 

Joel Kontinen

Can we turn wastewater into fuel?

"Wastewater, which is full of pollutants that contain nitrogen, can be directly fed into a new chemical reactor that converts it into ammonia, with purified water and oxygen as by-productsThe sustainable alternative requires much less energy than the conventional method for producing this crucial chemical.

Agriculture, refrigeration systems, paper, cleaning supplies and other industries use hundreds of millions of tonnes of ammonia every year. Making that much of the chemical uses about 2 per cent of energy total energy consumption and contributes 1.4 per cent of global carbon dioxide emission.

Some of this environmental price is due to the conventional way of producing ammonia, which requires high temperatures and pressures. To make ammonia production more sustainable, Feng-Yang Chen at Rice University in Texas and his colleagues wanted to replace that technique with a room-temperature reactor.

Their reactor takes in water mixed with nitrates – nitrogen compounds often found in wastewater, such as industrial sewage or agricultural runoff contaminated with nitrogen-based fertilisers. After the nitrate water enters the first of three chambers, electrodes, similar to those found in batteries, create an electrochemical reaction that transforms the liquid into three components: only ammonia remains in the first chamber of the reactor, while purified water flows out through the second one and oxygen goes to the third."

It is the things that are hidden in wastewater – nitrogen and ammonia that can turn wastewater into fuel.

 Source:

Karmela Padavic-Callagh, 2024. We could make fuel and fertiliser by recycling wastewater | New Scientist 12 August