Scientists make world water nano-clean
by Geraldine Hinter
UniSA
scientists have discovered a simple way to remove bacteria and other
contaminants from water using tiny particles of pure silica coated
with an active nano-material.
The unique water treatment process has the potential to make a significant contribution to human health worldwide in as little as two years.
Professor Peter Majewski and PhD student Chiu Ping Chan from UniSA’s School of Advanced Manufacturing and Mechanical Engineering developed the new technique, which can remove bacteria, chemicals, viruses and other contaminants from water much more effectively than conventional water purification methods.
"Its major benefits include an easy-to-use chemical and physical treatment process that cleans water without requiring additional energy, and uses recyclable non-toxic base materials such as the waste product silica and water, which brings costs down," Prof Majewski said.
"These features make it a very attractive alternative to desalination, which incurs high energy costs," he said.
Prof Majewski says the technology will make an important contribution to solving water quality problems globally.
The recent UNESCO report, Water for People – Water for Life, reveals that more than 6,000 people die every day from water-related diseases, and the availability of quality drinking water, especially in the developing world, is fast becoming a major socio-economic issue.
The report also indicates that waste water pollutants from industries including pulp and paper mills, textiles and leather factories, steel foundries and petrochemicals refineries are a major cause of illness in parts of the world where inadequate regulations leave people subject to toxic industrial outflows.
Prof Majewski says current water purification techniques are complicated and use sophisticated equipment – often expensive to operate and maintain - and include a final, costly disinfection stage.
"Our technology is simple," he said.
"We coat tiny silica particles with a nanometer-thin layer of an active material based on a hydrocarbon with a silicon-containing anchor."
The coating is made by a chemical self-assembly process, which involves simply mixing the ingredients to make what is called active ‘surface engineered particles’.
"We put the prepared particles in the contaminated water and stir it, or flush the contaminated water through a filter containing the active particles, which is much easier to handle. As the water runs through the filter, the toxins attach themselves to the coated particles through an electrostatic attraction between the contaminants and the particles and remain in the filter, leaving good quality water of drinking standard," he said.
Testing of the active particles demonstrates that they can remove pathogens such as the Polio virus, bacteria such as Escherichia coli, and the waterborne parasite Cryptosporidium parvum.
In addition to cleaning water for drinking, UniSA’s water purification technology is suitable for a broad range of uses including home use such as cold water refrigeration to ensure that there is no bacterial contamination, and for cleaning swimming pools and ornamental ponds.
Prof Majewski says that all water can be treated and his researchers are looking into processed water treated for reuse in industry, which requires fewer regulations than drinking water.
"UniSA’s water purification process using nanotechnology could help to prevent disease and poisoning for millions of people worldwide," he said.