KAUST scientists have developed a new peel-off, nontoxic coating that can be used to clean desalination membranes.
According to scientists, the new coating offers a more safer and efficient alternative to harmful chemicals used for cleaning desalination reverse osmosis systems.
Reverse osmosis desalination uses pressure to filter seawater through a semipermeable membrane to produce fresh drinking water.
While this technique is more energy efficient than other desalination approaches, its performance is hindered by the growth of bacteria and other microorganisms on the membrane surface.
This in turn creates a layer on the biofilm that does not allow water to pass as easily, notes Maria Fernanda Nava-Ocampo, a Ph.D. student under the supervision of professor Johannes Vrouwenvelder.
“One of the biggest problems of all the current methods to control biofouling is that they do not completely remove the biofilm from the membrane system, resulting in permanent fouling.”
“This causes elevated energy consumption and disposal of control chemicals into the sea.”
Nava-Ocampo and her team have now developed a new polyelectrolyte coating that avoids the need for toxic linkers to be attached to the membrane.
It can also be safely flushed out of the system with brine and increased flow, leaving the membrane surface clear of biofilm.
“The advantage of our coating is that it attaches to the surface by electrostatic interactions, so we don’t have to use chemicals,” says Nava-Ocampo.
“We also don’t have to pretreat the membrane in order to coat it. The membrane stays in the system and we just pass the coating through the same current flow used for desalination.”
According to the scientists, the coating remains stable in salty water, making it suitable for seawater desalination.
All one has to do to remove the coating and attached biofilm from the membrane is to increase the strength of the water flow and water salinity.
This cleaning process also ensures that the flow of liquid through the coated membrane is two-fold higher than the non-coated control.
Nava-Ocampo and her team are now working on making this coating more efficient and durable at larger scales.
Image and content: Xavier Pita/KAUST