National Physical Laboratory

Busting bugs with bubbles

A novel ultrasound processor is being developed to kill bacteria in water.

The Challenge

Busting bugs with bubbles
Left to right: Mark Hodnett (NPL), the late Henry
Ratcliff - the inventor, Bajram Zeqiri (NPL) and
Trevor Baylis

A UK SME, Ultrasonic Processors Ltd (a Joint Venture between Ultrasonics Technologies Ltd and Trevor Baylis Brands plc), has developed an ultrasound processor with the potential to kill bacteria. The high efficiency system could be used in water treatment plants and also in cleansing domestic supplies, and would be of particular benefit in remote areas where currently expensive UV treatment processes are used.

This new processor is reliant upon producing large numbers of imploding cavitation bubbles in order to break down bacterial cells. To aid optimisation of the technical design, as well as provide an on-line monitor to give immediate warning of process failure, a cavitation detector is highly desirable. However, there are currently no commercially available sensors that can reliably measure acoustic cavitation.

The Solution

The SME was very interested to learn of a novel instrument, developed and patented by NPL, which can detect and monitor the acoustic signals produced by cavitation bubbles. Through a short consultancy NPL were able to use the sensor to show that the processor was very effective at producing cavitation bubbles in static conditions.

NPL's Mark Hodnett was seconded to the SME to enable further investigations of the processor under industrial flow conditions, and also to examine correlations between cavitation activity and 'bug kill' during trials at a clean water treatment plant, looking for evidence of reductions in concentrations of coliforms and E. coli.

Although it was difficult to draw firm conclusions from this first industrial trial the results suggest that the processor does have the capability to improve the sanitary quality of water. With the confidence that the invention is on the right tracks, the SME is now optimising the processor design.

"Ultrasonic Processors Ltd has benefited enormously from the help and support given by NPL under the DTI Consultancy and Secondment schemes."
David Bunting, Director of Ultrasonic Processors Ltd

Find out more about NPL's research in Ultrasound

Do you have a measurement challenge that you'd like NPL's help with? If so, why not apply for NPL's Technology Innovation Fund ?

Last Updated: 9 Oct 2012
Created: 3 Jun 2010

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