This is how drug residues can get into the Danube
The Water Science of the National Academy of the Hungarian Academy of Sciences has been researching the effects of endangering the safety of drinking water for three years. The project entitled “Clean drinking water: a multidisciplinary assessment of safe supply from source to consumers” supported within the framework of the NKFIH National Program of Excellence aims to study the coastal filtered drinking water system supplying nearly two million inhabitants of Budapest and its agglomeration.
Water samples were taken from around Budapest
The research of the consortium defined by the Ecological Research Center, the Budapest University of Technology and Economics, the National Center for Public Health, the University of Miskolc and Fővárosi Vízművek Zrt. are aimed at detecting micro-contaminants. The bi-weekly sampling, covering all seasons and different water levels of the river, covered the water base above and below Budapest: from the Danube water base through the coastal filtered wells and drinking water treatment technology points to the distribution network.
During the annual sampling program, the National Center for Public Health was responsible for the identification of organic micro-contaminants, including various antibiotics and antibiotic-resistant microorganisms. A total of more than 45,000 measurements were made from the 870 Danube water, well water and network water samples.
Residues of drugs enter surface waters mainly from municipal effluents or, in the case of veterinary use, from agricultural effluents. To the best of our knowledge, conventional biological wastewater treatment as well as the third stage of nutrient removal treatment are not able to completely remove organic micro-contaminants.
However, in the case of rivers with a flow such as the Danube, low concentrations must be achieved, even in the immediate vicinity of large cities, due to the high dilution. The concentration of clarithromycin, an antibiotic presented as an example, was typically below 10 ng / l in the Danube water, and at most sampling times there was no significant difference between the upstream and downstream samples from Budapest. Temporal variability in the concentration of drug residues is influenced by several factors: seasonal variable use, water yield, rate of biological or photodegradation, which may be most effective during the winter months.
Drug residues: can they get into drinking water?
The exact effects of drug residues and other organic micropollutants on surface water life for most substances are unclear. It is also a common concern that these substances may enter drinking water.
The northern and southern shore-filtered wells supplying Budapest rely primarily on the natural cleaning capacity of the Danube gravel bed. The biological and chemical decomposition and absorption processes in the sediment remove most contaminants with high efficiency. In our example, the concentration of clarithromycin during shore filtration dropped below the detection limit in almost all cases and was not detectable in the mains water. One of the main tasks of the remaining term of the project is to identify the factors influencing the removal efficiency of different contaminants through the analysis of hydrological variables.
The streams around Budapest are polluted by drug residues – read on!
The presence of antibiotics in surface waters has emerged for the environmental spread of antibiotic resistance. While the so-called. faecal indicator of bacteria such as E. coliResistant strains are also typically of wastewater origin, and resistance in environmental bacteria may be the result of horizontal gene transfer in environmental “hot spots”.
Antibiotic-resistant bacteria in the Danube
The “Clean Drinking Water” project examined, among other things, bacteria belonging to the Enterobacteriaceae family resistant to 3rd generation cephalosporins, which are among the most clinically significant antibiotic-resistant organisms. The E. coli The effect of Budapest as a source of pollution was much more observable in the number of germs of coliform and coliform bacteria: the water quality of the Danube was significantly worse in the southern sample area. There was no significant difference only in the proportion of resistant strains, both above and below Budapest, approx. It was 0.5%. The majority of isolates showing 3rd generation cephalosporin resistance are Enterobacter and Citrobacter belonged to the genus, which is widespread, common in bacteria in the waters, although it is Enterobacter aerogenes and that E. cloacae it is also a significant species for nosocomial infections.
Coastal screening is also well-tested for the removal of microbiological contaminants: faecal pollution in well and network waters E. coli was not detectable in any of the samples.