Conventional wastewater treatment plants are unable to adequately filter and clean the drug residues. In the second stage, the mostly mechanically pre-cleaned wastewater with the help of microorganisms - ie bacteria - cleaned. Above all, organic substances are degraded, eg. B. from food residues and feces.
In the further wastewater treatment, chemicals such as phosphates and heavy metals are precipitated and flocculated by the use of chemicals and removed from the water. What remains is bulking sludge, which must be stabilized. The solid residues are used for agriculture, landfilled or incinerated.
Degradation of medicines
But how the breakdown of medicines takes place and which decomposition products arise is only clarified in individual cases. Probably drugs are not only converted to carbon dioxide and bacterial mass during biological, oxidative degradation. It also presumably results in degradation products that can no longer be detected with today's analytical methods.
Dr. Manfred Hilp, pharmacist and graduate chemist, writes in the Pharmazeutische Zeitschrift that eg ibuprofen shows a "bad environmental behavior". It was detected in drinking water, while in acetylsalicylic acid (ASA) despite the much higher consumption of salicylic acid was found only in traces in streams.
Modern methods demanded
Scientists demand that wastewater treatment be technologically upgraded - for example, nano- or microfiltration or activated carbon processes are in demand. Technically, this is possible: A Europe-wide observed pilot project for the treatment of wastewater from a hospital is currently underway in Oberbergischen Waldbröl near Cologne - leading is the Institute for Urban Water Management of the RWTH Aachen (ISA) to Prof. Johannes Pinnekamp.
Project manager Silvio Beier explains: "For the first time, the entire wastewater stream of a hospital is treated with a separate wastewater treatment plant." Thus, residues of X-ray contrast agents, antibiotics, lipid lowering, beta-blockers or anti-inflammatory drugs can be significantly reduced, an elimination of 30 to 99 percent, depending on the pharmaceutical substance, is possible.
In post-treatment steps, virtually everything can then be cleaned and only a lot remains in the no longer measurable area. Several processes for aftertreatment - such as using ozone or activated carbon - are currently being tested by the institute and by project partners for maximum effectiveness and cost-effectiveness.
Federal Environment Agency expert Dieter sees no reason to sound the alarm or even to give up tap water. But: "The problem is increasing and we have to do something now." As life expectancy increases and more and more prescription drugs become available, the amount of medication taken - and later excreted - will also increase.
After all, every single one of them can behave so responsibly that medicines should generally be handed over to the pharmacy for disposal. The prescribed remedy should always be taken as directed by the doctor or pharmacist. You should never take over-the-counter painkillers too often, and be sure to read the leaflet.