A team of scientists from the University of Dhaka, Bangladesh and Uppsala University, Sweden have jointly developed a nano-filter paper from a Bangladeshi variety of microalgae, Pithophora, locally known as a type of “Shewla” [শেওলা]), which has demonstrated excellent virus and bacteria removal capacity. The scientists believe that with further development, this nano-filter paper could become an affordable and efficient solution to prevent potentially deadly water-borne infections, thus saving millions of lives. The work started in 2017 with another microalgae species in mind, Cladophora, used by the Uppsala group for their earlier research. Although Cladophora is available in Bangladesh, but is difficult to grow and harvest in a pure form for large scale applications. The suggestion of using Pithophora came from the botany experts of Dhaka University team. They also developed methods of cultivation of Pithophora that gave a very high output. Harvested, cleaned and dried Pithophora was sent to Sweden where the filter paper was made and tested in laboratories under controlled conditions for bacteria and virus removal. Side by side, its effectiveness was also tested for river and lake water in Bangladesh at the Department of Microbiology of the University of Dhaka. The above studies showed that the filter paper could remove more than 99.999% of bacteria and viruses. However, it required a relatively high pressure of about 5 bars to produce an acceptable volume of water output which would be a limitation of this filter paper under its present form. Further work needs to be done to modify the technology of making the filter paper so that it could work at low pressures, suitable for use by people at their households. A paper on the work was published in a reputed journal, ACS Sustainable Chemistry & Engineering (Gustafsson et al., 2019).

The Dhaka University team members were, Professor Dr. Mohammed Almujaddade Alfasane of the Department of Botany, Professor Dr. Anowara Begum of the Department of Microbiology and Dr. Sharmin Zaman, a research scientist at the Centre for Advanced Research in Sciences. Dr. Albert Mihranyan, Nanotechnology and Functional materials, Department of Engineering Sciences at Uppsala University of Sweden led the whole research work while the Bangladesh part of the work was led by Professor Khondkar Siddique-e-Rabbani, Honorary Professor, Dept. of Biomedical Physics and Technology who liaised with the Swedish group in planning and organising the Bangladesh part of the work and analyzing the results.

The Dhaka University team is contemplating using the Pithophora algae to prepare nano-cellulose locally (if project support is available) which would be highly absorbent and could be used in various applications including making biodegradable sanitary napkins. It may also have potential in making biofuels and nano-carbon sheets, the latter to make supercapacitors to replace batteries in electronic circuits.

Reference: Gustafsson O, Manukyan L, Gustafsson S, Tummala GK, Zaman S, Begum A, Alfasane MA, Rabbani KSE, Mihranyan A. 2019. Scalable and Sustainable Total Pathogen Removal Filter Paper for Point-of-Use Drinking Water Purification in Bangladesh. ACS Sustainable Chemistry & Engineering, 7, 17, 14373-14383; DOI: 10.1021/acssuschemeng.9b03905.

PHOTO: The Bangladeshi Team (from left to right): Professor K S Rabbani, Professor M A Alfasane, Professor A Begum and Dr. S Zaman