Although X-ray contrast agents (German: "Röntgenkontrastmittel", RKM) are considered harmless to humans and the environment, these chemicals are accumulating more and more in our waters. The reason for this is their stable composition: As a result, it is almost impossible to remove them in sewage treatment plants after they have been discharged from the patients and have entered the sewage system. The "MERK'MAL" project of the Mülheim IWW Zentrum Wasser and the Duisburg Institut für Energie- und Umwelttechnik e. V., IUTA, has found a solution which reduces the RKM concentration in bodies of water, using the Ruhr River as an example.
Urine bags were distributed in medical facilities in Mülheim for four months to patients who had previously been given RKM. They were to use the containers during their first visits to the toilet after the examination. In the bags, the urine is converted into a gel and then disposed of with household waste. With proper guidance, support in organization and communication, the concept can be implemented with minimal effort for medical partners. And the results are convincing: One survey showed that up to 87 percent of patients actually used the bags. In Mühlheim alone, several hundred kilograms of RKM could be retained; according to projections, this would amount to four tons of RKM per year in the entire Ruhr catchment area. The concentration of RKM in the river could thus be approximately halved if the procedure were to be consistently implemented throughout the entire Ruhr area. For this reason, the project is now to be extended to the Ruhr's core catchment area.
