Algae extract forms filter for safe drinking water

Clean drinking water could be more widely available in Bangladesh following the development of a point-of-use filter made from the cellulose nanofibres found in a form of algae.

point-of-use filter
Paper filter made from Pithophora algae (Credit: Albert Mihranyan)

Scientists from Uppsala University, Sweden, and Dhaka University, Bangladesh, have shown that cellulose nanofibres can be extracted from Pithophora algae which can be formed into filters with tailored pore sizes.

The performance of the filter has been validated using surrogate latex nanobeads, in vitro model viruses, and water samples collected from the Turag River and Dhanmondi Lake in Dhaka.

“Pithophora algae have been largely overlooked in the past as a valuable raw material. It is with great satisfaction that we can now document excellent pathogen removal clearance for both water-borne bacteria and viruses with efficiency above 99.999 per cent. It can purify even the smallest virus particles of 27-28 nanometres”, said Albert Mihranyan, Professor of Nanotechnology at Uppsala University, who heads the study.

By 2050, projected growth rates suggest that the population of Bangladesh may reach 200-225 million people. In parts of Dhaka or Chittagong, Bangladesh’s largest cities, the density of population is as high as 205,000 inhabitants/km2. Hyper-high density of population, poor hygiene, and lack of clean water increase the risk of spreading water-borne infections.

Dhaka and Chittagong do have extensive piped water and sewage systems, but even there the water is available for a few hours per day and may still be contaminated with infectious pathogens due to leakage in pipelines.

Boiling, sunlight pasteurisation, or chemical disinfection are a handful of methods currently used for point-of-use water treatment. Similarly, filtration is an effective way of treating water to physically remove pathogens. Consequently, new types of affordable point-of-use filters that can remove all kinds of pathogenic bacteria, spores, and viruses are in high demand.

“Access to clean water will contribute strongly to improved health thus reducing poverty. We are optimistic that through future development of devices the filter paper produced from the locally growing algae will be useful to prevent potentially deadly water-borne diseases and improve the quality of life for millions of people” said Khondkar Siddique-e-Rabbani, Honorary Professor at University of Dhaka and project coordinator in Bangladesh.

A paper outlining the work is published in ACS Sustainable Chemistry & Engineering.