Researchers from the University of Bath created a new desalination process that could be operated in mobile, solar-powered units. The new device is low cost, low energy and low maintenance with the potential to provide fresh water to communities in remote or disaster-stricken areas with little to no freshwater supply. It is a low energy system with no moving parts.

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The 3D printed system has two internal chambers that extract and accumulate salt. When power is applied, salt cations and salt anions flow between the chambers through an array of microholes in thin synthetic membrane. The flow only happens in one direction, pumping salt out of the water.

In the classic desalination process, water is pumped through a membrane, rather than salt. This is an energy-intensive process that is carried out in industrial plants. But there are times when a small solar-powered desalination unit would be beneficial. Large industrial power plants are essential, but they aren’t helpful in remote locations or a coastal catastrophe.

The Bath University desalination system is based on iconics. It is a cationic diode combined with anionic resistor. By increasing the concentration of salt, waste is minimized - the separated salt can be crystalized and reused. Most desalination processes pump salt back into the sea as brine, which unsettles the marine ecosystem.

Before the unit can be rolled out, the team needs to find more robust materials to refine and scale up the device. The proof-of-concept prototype can only remove 50 percent of salt from a saltwater sample. Salt needs to be reduced by 90 percent to be considered freshwater. The team also needs to find better porous materials that can pump ions.

The team is testing bacteriophages, viruses that infect and replace within bacteria. This could create the material that the team needs. The nano strands stick together and create a thin film with tiny holes. It worked well when tested, but the material disintegrates as salt content and pH rises. For the material to be used in a device it the team needs to improve its semi permeability.

A paper on this research was published in Desalination.