Yang-Hui Cai from the IAMT at KIT using a filtration experiment to investigate the efficacy of the naturally occurring osmotic backwash process for cleaning deposits. (Image: Andrea Schäfer, KIT)
Yang-Hui Cai from the IAMT at KIT using a filtration experiment to investigate the efficacy of the naturally occurring osmotic backwash process for cleaning deposits. (Image: Andrea Schäfer, KIT)

Researchers from the Karlsruhe Institute of Technology (KIT) have been examining natural cleaning processes for photovoltaic-operated membrane filter systems to help provide more clean drinking water in developing countries.

Decentralised battery-free membrane filter systems operated with photovoltaics can help improve drinking water supplies. However, dirt and deposits such as limescale on the membrane increase energy consumption, and the filter must be chemically cleaned on a regular basis.

The KIT scientists have investigated the efficacy of using natural osmotic backwashing and the results of their research have been published by Elsevier in the Journal of Membrane Science (Volume 619, 1 February 2021, 118799).

Yang-Hui Cai from the Institute for Advanced Membrane Technology (IAMT) at KIT, said: "If the solar energy fluctuates in such photovoltaic-operated membrane filter systems, this can lead to the operating pressure being lower than the osmotic pressure - this means that clean water flows back through the membrane and removes the deposits from the membrane surface in a very short but powerful process. Our results show that this backwashing works well as a natural cleaning process."