Micro-pollutants in water circulation

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Source: WEDECO - a Xylem brand

The elimination of micro-pollutants from our water is a challenge which more and more responsible providers and disposers have to set themselves. While biological treatment processes do not remove them completely, oxidation with ozone is proving to be one of the most efficient methods.

Pharmaceuticals help many people and animals when fighting diseases, keeping healthy or improving quality of life. Nonetheless, a large proportion of pharmaceutical agents end up in the environment via sewage from bodily excretion.

Although they do not constitute an immediate hazard there, it is the long-term dangers that are becoming ever more significant. The effects of micro-pollutants or of pharmaceutical substances in surface waters have already been proven on numerous occasions in large-scale studies and lead to negative changes in the ecosystem and therefore to problems.

Problem I: Persistence

Not all approved substances in the area of pharmacy, agriculture and industry as well as in the area of daily consumption are completely biodegradable. This means they cannot be fully removed with conventional clarification technology. As a result, the number of contaminants in our water circulation and its consumers is creeping upwards (bioaccumulation).

This means a constant rise in water pollutants and further negative effects for the aquatic environment for the future, unless appropriate measures are taken.

Problem II: Endocrine effect

Some micro-pollutants (e.g. the active ingredient of the pill (ethinylestradiol)) has an effect on the hormonal system of humans and animals. These so-called endocrine substances (EDCs) are effective from the lowest of concentrations and are classified by science as particularly critical. In connection with negative environmental influences on living creatures, EDCs are currently being considered as elicitors:

  • Negative effects on the reproduction of certain kinds of fish are being observed (including the “feminisation” of male fish)
  • The fertility decrease in humans and animals due to reduced sperm quality is going up
  • The increase of certain types of cancer which could be related to a disturbance of the hormonal system

The special agent: Ozone

The effects of endocrine substances and persistent micro-pollutants on our ecosystem mean that more extensive purification is necessary. Many wastwater treatment plants reach their limits in eliminating the pollutants to a sufficient extent with existing purification technology. Numerous pilot tests with ozone as a further treatment step have shown that ozone is a suitable means for eliminating persistent pollutants. This means that micro-pollutants present in water can be effectively removed with ecologically and economically worthwhile doses of ozone.

How does OZONE work?

Ozone is one of the most powerful technically produced, gaseous oxidants. It reacts quickly with a large number of compounds. In doing so these compounds are attacked either directly by the ozone molecule or indirectly by the intermediately occurring hydroxyl radicals. Ozone reacts quickly with micro-pollutants containing accessible amino groups, double bonds or aromatic systems. Alongside these pollutantspecific attributes, the efficiency of the reactions also depends on the pH value and on the dissolved organic carbon (DOC).

Successful pilot tests with ozone

WEDECO ozone systems have already been used for several national as well as international projects for reducing micro-pollution and tested on an industrial scale:

  • EU project POSEIDON, Braunschweig wastewater treatment plant January 2001 – June 2004 (Project No. EVK1-CT-2000-00047)
  • National project of Switzerland “Strategy MicroPoll”, Wüeri wastewater treatment plant in Regensdorf, July 2007 – October 2008
  • “PILOTOX” project, Technical University of Berlin, Berlin Ruhleben wastewater treatment plant, December 2004 – July 2005
  • EU project POSEIDON, EAWAG, Zürich/Opfikon wastewater treatment plant, November 2003
  • Research project at the University of Stuttgart, Büsnau wastewater treatment plant, December 2003 – May 2005
  • “KomOzon” project, Technical University of Vienna, Vienna wastewater treatment plant, 2007 – 2009.

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