1/2016

Laser reveals water impurities

What could take hours of manual work with laboratory samples, a laser beam may find in ten seconds. An invention made at TUT is a future solution for analyzing water impurities in industrial applications and at water treatment plants, for example.

Juha Toivonen and Samu Järvinen

 

Juha Toivonen and Samu Järvinen feel confident that the developed method can be turned into a functional commercial product.

 

Several fields of industry use water in their processes. In order for everything to work as it should and to have clean discharge water, it is important to analyze water impurities as frequently as possible. At the moment, detailed measurements from samples are taken manually in laboratories. Therefore, industry has a clear demand for better and faster methods.

“Analyzing water impurities with a laser is a project that set off based on an explicit need and upon the mining industry’s initiative,” Associate Professor Juha Toivonen from TUT’s Department of Physics and the head of a research group for applied optics relates.

This newly invented method was developed by Samu Järvinen, a doctoral student at the Department of Physics, through collaboration between the Optics and Aerosol Physics laboratories. Järvinen’s doctoral dissertation will be examined this spring. The method involves taking a drop of water as a small specimen for the measurement device and then levitating the droplet in an electric field. As the droplet dries out, the relative impurity levels in the specimen increase, facilitating measurement. The laser scatters the impurities into atoms and measures the levels.

“The measurement method combines optics and aerosol studies. Being an optics researcher, atomization with a laser was the most fascinating aspect for me. The biggest challenge was learning to levitate the droplet. To learn it, we obtained support from the University of Bristol,” Samu Järvinen explains.

Research targets of the research group for applied optics

  • Laser-based gas content measurements and related applications in combustion technology
  • Element specification of water impurities
  • Optical perception and imaging of ionizing radiation
  • Laser radar, i.e. LIDAR methods
  • Application of fluorescent nanoclusters in polymer films
 

Enhanced information, faster reactions

There are many areas in which accurate information on water impurities is required.

“The mining, metal, paper and chemicals industries. Oil refining, environmental control and waterworks,” Järvinen lists.

With industrial waters, it is possible to measure secondary aspects, such as opacity, conductivity and pH levels with a high level of automation, but more detailed impurity results have thus far required laboratory tests. Therefore, process adjustment has been very slow.

Samu Järvinen’s measurement method could replace laboratory tests, at least for the most part.

“Today, perhaps 1–2 tests are taken each day, and the results are often only available on the following day. With laser measurement available, there would be a far less frequent need for manual analyses, perhaps only once or twice a week. The equipment would manage all intermediate-phase measurements – every ten seconds, around the clock,” Toivonen explains.

At water treatment plants, for example, a sulphate solution is currently used for phosphorus removal based on the average measurement to ensure that the water has been purified.

“A higher level of detail with the water contents enables faster and more accurate reactions, however,” Toivonen continues.

“Not everyone around the world is as lucky with clean drinking water as we are here in Finland. This equipment could be used as an alarm system for dangerous water impurities elsewhere in the world.
There are many possible applications for this, and we do not even comprehend the full potential yet,” Järvinen notes.

Towards commercialization

Samu Järvinen analyzed the potential of his idea in a commercialization project that came to an end this autumn. The project involved discussions with roughly 20 companies. Many were interested. The researchers feel confident that the developed method can be turned into a functional commercial product.

“The methods we applied, such as the water droplet levitation and the content measurement of chemical elements, have already been tried and tested in other contexts – and found highly functional. The same laser that measures element contents is used in the Mars Exploration Rover, for example. In other words, what we have done now is a new combination of a couple of previous inventions. We have a long way to go before we have a commercially available product in our hands, however,” Juha Toivonen says.

One patent application is already pending. The goal is to have the invention on the market in a few years.

“I will first have to finish my dissertation project this spring, and then we will pay a few visits to startup investors,” Samu Järvinen comments.

Text and photo: Sanna Schildt

 
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