Bacteria-based water filter twice as fast as existing techniques

The group claims that its ultrafiltration membrane, which uses graphene oxide and bacterial nanocellulose, could be scaled up and used to provide clean drinking water for people in developing countries. More than one in 10 people in the world lack basic drinking water access, and by 2025, half of the world's population will be living in water-stressed areas,

Developed by Professors Srikanth Singamaneni and Young-Shin Jun, the water filter membrane was made by feeding Gluconacetobacter hansenii bacteria a sugary substance so that they form cellulose nanofibres when in water. The team then incorporated graphene oxide (GO) flakes into the bacterial nanocellulose while it was growing, essentially trapping GO in the membrane to make it stable and durable.

After GO is incorporated, the membrane is treated with a base solution to kill Gluconacetobacter. During this process, the oxygen groups of GO are eliminated, making it reduced GO. When the team shone sunlight onto the membrane, the reduced GO flakes immediately generated heat, which is dissipated into the surrounding water and bacteria nanocellulose.