World Water Day 2010 – Water pollution from medication poses a new challenge for UV purification

The treatment of drinking water with UV radiation is a very effective physical process for reliably disinfecting water. The energy-rich light of a wavelength of 254 nanometers destroys the genetic make-up and, in seconds, destroys the cells of the pathogens present in the water. Ultraviolet light is particularly effective on parasites which are chlorine-resistant. As the purification takes place without chemicals and there are no chemical residuals the quality of the drinking water is not impaired in terms of taste or smell. The history of UV purification already goes back 100 years. The first patented purification with UV light took place in France in 1910 using quartz glass lamps – a development going back to the work of Richard Küch (chief developer at Heraeus from 1890-1915) in 1904. In 100 years much has changed. “Today’s requirements and challenges for UV lamps focus on significantly increasing efficiency and operating life,” states Dr Sven Schalk, business leader for UV Process Technology at Heraeus. The manufacturer of special light sources has developed innovative high power amalgam lamps for potable water treatment, which can be operated for up to 16,000 hours at virtually constant UV output. Thanks to their unique Longlife coating, they carry on working for twice as long as conventional standard low pressure lamps.

But UV radiation isn't enough to treat water polluted with pharmaceuticals on its own. With the “Advanced Oxidation” process ultraviolet radiation can break down pollutants in the water. “As distinguished from water disinfection, in Advanced Oxidation vacuum UV radiation below 250 nanometers is used. The properties of this still energy-rich UV light are used in water purification are used to destroy substances in the water which are biologically difficult or impossible to break down. Chemical compounds are decomposed or more precisely converted and thus destroyed and made ineffective”, Sven Schalk describes. The Advanced Oxidation process is carried out with UV radiation and a combination of ozone or alternatively hydrogen peroxide or both.

The advanced oxidation process relies on UV radiation in combination with ozone, hydrogen peroxide, or both. In Germany, this water treatment process is still only used to purify gray water. However, it's a different story in the Netherlands. For example, the largest and most modern waterworks in the Netherlands PWN in Andijk, no longer uses just UV equipment for the disinfection of drinking water but has also introduced additional processes using Advanced Oxidation to destroy pollutants in ground water. Around 25 million cubic meters of dirty water are treated here every year.