Conventional ultrafiltration membranes are prone to clogging during water purification, a problem addressed with a living filtration membrane engineered by researchers from Montana Technological University and Arizona State University. The thin, permeable symbiotic culture of bacteria and yeast (SCOBY) membrane was developed by fermenting a blend of sugar, black tea, distilled white vinegar and water.

Stacked sheets of cellulose produced from the microbial culture, more commonly used to produce the fermented drink known as kombucha, can be tuned to filter different sizes of particles and are self-healing. The SCOBY microbes also produce antibacterial acetic acid, an agent of value in preventing biofilm formation.

The performance of the new device and of a commercial polymer membrane in filtering reservoir and river water were evaluated. Both materials clogged and filtered more slowly over time, but the SCOBY-sourced membrane resisted fouling better and maintained faster filtering, especially with dirtier and microorganism-laden water samples. A biofilm that eventually formed in the living membrane was observed to host fewer microorganisms relative to the conventional filter, indicating that the presence of acetic acid-producing bacteria reduced biofilm development.

A research paper on the low-cost and biodegradable living membrane is published in ACS ES&T Water.

To contact the author of this article, email