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Fluorescence test can show water quality

People in disaster areas could one day test if water is safe to drink in seconds using technology under development at Birmingham University.

A team of engineers and scientists are developing a device that measures water’s fluorescence in order to detect harmful microbes and chemicals.

They plan to work with several water companies in England and Wales to test the device in the UK’s distribution system.

But they also hope it could also be deployed in parts of developing countries where there is no established water supply, as well as used by aid agencies assisting areas hit by natural disasters.

‘Normal tests for whether you’ve got microbial activity in the water or not can take three to five days,’ project leader Dr John Bridgeman
told The Engineer.

‘Using fluorescence we could give you an answer in seconds as to whether water is contaminated or not.’

‘In this country, water quality is generally assessed at the customers’ tap and there is little real-time quality management in the distribution system. If we put an instrument in the system it could measure the water quality and send the data to a control centre.’

Water, like other substances, can absorb certain wavelengths of electromagnetic radiation and then emit it at a different wavelength, a process known as fluorescence.

Bridgeman’s technology identifies where radiation absorbed and emitted at specific wavelengths creates high intensity fluorescence, indicating that water pollutants are present.

‘For example if we irradiate water at 280nm and receive an emission wavelength of about 360nm and get a large fluorescence intensity, we know that it is indicative of microbial activity – bugs in the water,’ said Bridgeman.

Other pairs of specific wavelengths correspond to other pollutants such as organic matter and whitening agents from detergents.

When chlorine is added to water to kill microbes, it can react with organic material to produce disinfectant by-products such as trihalomethanes (THMs). Low-level exposure to these over a long period of time can cause cancer.

Bridgeman is leading two projects related to the technology, funded by EPSRC grants of around £200,000 and £450,000, respectively.

The first involves testing water in Durban, South Africa, for microbes and correlating the results with laboratory analysis to ensure the process is robust enough to work in different environments.

The second involves constructing an LED device to detect both microbes and organic matter that will be tested at Sheffield University and then in the water system. The tests are expected to be complete by April this year.

Berkshire-based firm Safe Training Systems helped the team construct a device for the South Africa trials, while Northumbrian, Severn Trent and United Utilities water companies are assisting with the UK project.

The next step for the Durban project will be to speak to non-governmental organisations about the device’s possibilities for the developing world and disaster aid.


Readers' comments (2)

  • Good, but you can try it with a blue LED? This is the principle of Scintillation.

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  • Very interesting. Hope these test methods get operational in 2011. Am particularly interested to know the length of the "prolonged period" stated in para 12 as here in Jamaica this method for water purification is widely encouraged but I have never seen any statement about THMs accompanying State or other Agency publications which encourage the use of chlorine for water purification.

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