Hydraulic Symposium drug residues contaminate rivers

Hydraulic Symposium drug residues contaminate rivers. German rivers are contaminated not only by sewage and pesticides, but also by medicinal substances. Often the limit values ​​of funds are exceeded, as researchers reported at the RWTH Aachen Water Engineering Symposium.In the river Nidda, for example, large amounts of diclofenac were found.

Hydraulic Symposium drug residues contaminate rivers
The river Nidda is heavily contaminated with medicinal products. (Dpa / picture-alliance / Arne Deder)

The Nidda flows through Hesse. It springs from the Vogelsberg and flows into the Main. But actually there is everywhere:

“The Nidda is a river, as it is often found in Germany, a medium-sized river about 100 kilometers long.”

The environmental scientist Arne Wick from the Federal Institute for Water Sciences in Koblenz …

“The Nidda is also representative for rivers where we have a high settlement density but also a lot of influence from agriculture.”

Sewage and drains from fields flow into the Nidda

Wastewater from sewage treatment plants and drains from fields – they lead to the fact that the Nidda does not have the good chemical status which it should have had since the year 2015 according to the European Water Framework Directive. This results from measurement campaigns in the Nidda and its tributaries. Arne Wick reported on the preliminary results from the ongoing research project for the first time at the water engineering symposium in Aachen:

“There is definitely a need for action, but this is not just the case of Nidda, which is quite representative of all rivers that have a certain amount of sewage.”

Diclofenac, for example, is found in the purified wastewater from sewage treatment plants. The medicinal substance is found in many pain relievers. When washing hands after application or during showering, he gets into the sewage. And finally into the environment. In the sewage treatment plant Diclofenac rushes for the most part – so also at the Nidda. Still, there are no environmental quality standards for Diclofenac in the Water Framework Directive. But this is about to change soon:

“There is a proposed environmental quality standard, which is currently 50 nanograms per liter, which is actually exceeded in all areas, including the tributaries.”

Diclofenac damages kidneys of fish

The recommended threshold is therefore low, because it appears that tiny amounts of diclofenac are sufficient to damage the kidneys of fish. In the Nidda and its inflows, the annual mean values ​​for diclofenac significantly exceeded the 50 nanogram threshold. In some cases, the measured masses were ten times as high.

However, studies by the Rheinisch-Westfälisches Institut für Wasserforschung in Mühlheim an der Ruhr confirm that other rivers also have a problem with the inflammation inhibitor. There, the hydrologist Tim from Beek deals with water pollution by drugs:

“We have found over 4,000 readings for Diclofenac in Germany alone, and the average is over 0.1 micrograms per liter, which is above the limit, the so-called predicted no effect concentration To the environment. ”

High concentration of plant protection product Isoproturon

In the Nidda, isoproturon was also found to be caused by excessive levels in the water – a frequently used plant protection product. Farmers use it to control arable land. The substance also inhibits the photosynthesis of green algae in water bodies. For isoproturon the water frame directive therefore already has limits.

“In this case, we have seen an exceedance of environmental quality norms with regard to the maximum concentration. As soon as the situation of a substance exceeds the environmental quality norm, measures have to be taken.”

Switzerland has decided to do so. There, municipal sewage treatment plants receive a fourth cleaning stage. Partly they get activated charcoal filters, in some cases the waste water is additionally treated with ozone. Both methods can effectively eliminate substances such as diclofenac and isoproturon.

In Germany, too, there are now such considerations, as Tim from the Beek in Aachen said. For example in North Rhine-Westphalia:

“What is happening now in NRW is that you are more likely to find the hot spots, which means: Which wastewater treatment plants do we have particularly high entries for? Which wastewater treatment plants would it really be worth installing?”

Ecosystems in Germany are recovering only with difficulty

In Germany, the renaturation of rivers often does not have the hoped-for success, the ecosystem does not recover as expected. Researchers like Arne Wick suggest that this could also be due to the permanent exposure to pollutants such as diclofenac or isoproturon. One more reason from their point of view to reduce the entries of the substances.


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