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Water purification – ultraviolet style

Photonics Spectra
May 2010
Caren B. Les, News Editor, caren.les@photonics.com

Created by industrial designer Olivia Blechschmidt, the STER UV portable water sterilization device is tailored to the home kitchen environment. The tool aims to provide an effective alternative to boiling water in the home for those affected by contaminated drinking water, she said. Consisting of a UV light stir stick and induction charger, it was developed for rapid sterilization of drinking water directly in a glass, pitcher or other container.

“The STER UV is designed to sit on a kitchen counter, with the induction charger plugged in. One can simply remove the stir stick from its charging base, insert it into a glass of tap water, push the button for smaller volumes, give a quick stir and then wait until the UV lamp turns off,” Blechschmidt said. There are preset timers for glass size, 1 1/2 minutes, and for pitcher size, three minutes.

The water sensor exposes two metal plates that complete the circuit only when the stick is submerged in water, above the UV lamp, Blechschmidt explained. This removes the need for a power button and provides a safety measure that prevents users from having their eyes directly exposed to the UV lamp.

“The lamp applies 254-nanometer technology through a quartz protector. After the user gives a few quick stirs to the water container, the device can be left unattended while it continues to expose moving water molecules to the sterilizing light,” she said. Stirring allows all of the water molecules to be exposed to the UV light. The stick is long and lightweight so that it can be left unsupervised in containers of various sizes.

The induction charger is designed to continually power the stir stick when it is stored inside, and it incorporates a blue LED light power indicator. The charger also acts as a docking station that protects the stir stick and holds it in a ready-to-use position. With a 45-cm-long power cord, the charger can be plugged into standard kitchen outlets, eliminating the need for complicated installations in the plumbing system.

In terms of environmental friendliness, the induction charger eliminates the need for battery replacement and disposal. With no heat production or moving parts, the device uses less electricity than an electric toothbrush, Blechschmidt said, adding that use of the device also may discourage bottled water consumption, which has negative effects on the environment.

Boil water advisories

When asked how she became interested in the STER UV project, Blechschmidt said that the water purification market has been growing because of increased concerns over the quality of drinking water.

“In Canada, for example, where I worked on the device, the number of ‘boil water advisory’ days in various municipalities across the country increased by 24 percent between 1993 and 1998, and dozens of communities are under ‘standing’ boil water alerts that have remained in place year after year. Health Canada estimates unsafe drinking water causes 90,000 illnesses and ninety deaths every year.

“Bacteria and viruses pose the most immediate threat of illness or death and cause most drinking water emergencies. Although many home water filtration and purification systems have appeared on the market, they largely do not address the need for bacteria and virus removal, which is why people still resort to the tedious process of boiling water. Currently in Canada, there are no federal government regulations for water filtration products, such as those found in food and drugs by Health Canada.

Effectiveness of UV purification

“Ultraviolet light kills microorganisms such as bacteria (including E. coli), viruses, protozoa, gardia cysts and cryptosporidia by damaging the DNA. UV radiation disrupts the chemical bonds that hold the atoms of DNA together in the microorganism. If the damage is severe enough, the bacteria cannot repair the damage and will die. In contrast to chemical treatments, UV light penetrates the cells but does not alter the water being treated.

“Although UV light kills microorganisms, it generally has no impact on chlorine, heavy metals or other chemical contaminants. However, these types of pollutants are not life threatening and can be removed with many filtration devices on the market today.”


The STER UV water sterilization device is designed for use in residential kitchens. Photos courtesy of Olivia Blechschmidt.

The STER UV is designed to disinfect as well as to thoroughly boil drinking water. “The process of boiling water in the home typically means doing so in large batches, filling up pots with water, boiling over high heat and letting the water cool before distributing it into plastic bottles which then need to be stored. The STER UV could be a tool to ensure the availability of clean drinking water without advance planning or a long wait,” Blechschmidt said.

She added that it could be useful in any location that experiences boil-water advisories, particularly for rural homes that do not rely on a municipal water supply.

The product is not commercially available as of March 2010, but Blechschmidt said she would be happy to pursue its development for mass production if the opportunity to do so should arise.

The device has not been tested because the project was not taken as far as a fully functional prototype. However, the technology that it is based on – the application of UV light to sterilize water – has been tested and proved to be effective.


GLOSSARY
sensor
1. A generic term for detector. 2. A complete optical/mechanical/electronic system that contains some form of radiation detector.
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