MIT: Water desalination device

2022: A portable device has been released that turns salt water into fresh water. It consumes less power than a smartphone charger

At the end of April 2022, experts at the Massachusetts Institute of Technology presented a portable desalination device weighing less than 10 kg, which can remove particles and salts to obtain drinking water. A device that requires less power than a cell phone charger can operate from a small portable solar array.

Unlike other portable desalinizers that require water to pass through filters, this device uses electrical energy to remove particles from drinking water. Avoiding the need for replaceable filters significantly reduces long-term maintenance requirements.

A portable device that turns salt water into fresh water has been released

This may allow the use of the device in remote areas with limited resources, for example, in settlements on small islands or on board marine cargo ships. It can also be used to assist refugees fleeing natural disasters or soldiers conducting prolonged military operations. Commercially available portable desalinizers usually require high-pressure pumps to push water through filters, which are very difficult to miniaturize without compromising the device's energy efficiency, explains the researcher.

Instead, their device uses a method called ion concentration polarization (PKI), which was first applied by a group of scientists in 2010. Instead of filtering water, an electric field is applied to the membranes above and below the water channel during the PCI process. Membranes repel positively or negatively charged particles, including salt molecules, bacteria, and viruses as they pass by. Charged particles enter a second stream of water, which is eventually discharged to the outside. This process removes both dissolved and suspended solids, allowing clean water to pass through the channel. Since this requires only a low pressure pump, the PCI uses less energy than other methods. However, PCI does not always remove all salts floating in the middle of the channel. Therefore, the researchers included a second process, known as electrodialysis, to remove the remaining salt ions.

The researchers also created a smartphone app that can control the device wirelessly and report data on energy consumption and water salinity in real time. After conducting laboratory experiments using water with various levels of salinity and turbidity (haze), they tested the device in the field on Boston's Carson Beach. The resulting water exceeded the quality standards of the World Health Organization, and the device reduced the amount of suspended solids by at least 10 times. Their prototype produces drinking water at a speed of 0.3 liters per hour and requires only 20 watts of energy per liter.^[1]

Notes