Combination treatment produces ultrapure water
disinfect water can deliver a chemical-free knockout punch to
bacteria, according UK researchers.
Ozone is increasingly used as an alternative to chlorination in the modern food and drink industry, but normally only eliminates 99.99 per cent of bacteria. A research team at the University of Abertay Dundee say their method of combining the gas treatment with microbubbles destroys 99.9999 per cent of E.coli bacteria in a given volume of water.
The method is generating considerable interest among manufacturers seeking a means of ensuring ultrapure and almost completely bacteria-free water for use in food processing, they say. The treatment means that manufacturers can forego the use of the potentially harmful chemicals used to disinfect the water used in their processes.
Rashmi Chand, a doctorial student in Abertay's School of Contemporary Sciences, employed hydrodynamic cavitation technology to pump water very fast along a pipe and then through a small hole with such force that microbubbles or cavities are produced. The bubbles then implode, creating tiny pockets of high pressure and high temperature areas that kill bacteria.
The hydrodynamic cavitation by itself killed off 99 million out of 100 million E.coli cells in a body of water. Chand worked with David Bremner, a professor at Abertay, to investigate the effect of adding ozone.
They discovered that two bursts of the gas during the process further reduced the E.coli count to fewer than 100 cells.
"Conventional chemical disinfection techniques, particularly chlorination, suffer from disadvantages such as the formation of possibly carcinogenic by-products," Chand said "Our method of disinfection by means of ozone and hydrodynamic cavitation opens up the possibility of eliminating or drastically reducing the use of these disinfecting chemicals."
The project was supported by the Food Processing Faraday Partnership (FPFP), which aims to promote links between the UK science, engineering and technology community and the food manufacturing industry.
FPFP was interested in the specialised ultrasound and hydrodynamic equipment available only at Abertay. The organisation provided a grant to fund the acquisition of an ozoniser, allowing the six-month project to complete the research.
The Abertay team's results are due to be published in a scientific journal in the near future.
