The River Ruhr – an urban river under particular interest for recreational use and as a raw water source for drinking water: The collaborative research project “Safe Ruhr” – microbiological aspects

• Published in: International journal of hygiene and environmental health 2016-10, Vol.219 (7), p.643-661
• Main Authors: Strathmann, Martin, Horstkott, Marina, Koch, Christoph, Gayer, Uta, Wingender, Jost
• Format: Article
• Language: English
• Subjects: Bacterial pathogens; Drinking Water - microbiology; Drinking Water - parasitology; Drinking Water - virology; Environmental Monitoring; Fecal indicators; Feces - microbiology; Feces - parasitology; Feces - virology; Germany; Parasitic protozoa; Raw water; Recreation; Recreational water; River Ruhr; Rivers - microbiology; Rivers - parasitology; Rivers - virology; Water Microbiology; Water Quality
• ISSN: 1438-4639; 1618-131X
• DOI: 10.1016/j.ijheh.2016.07.005

Along the intense industrialization of the Ruhr valley (Germany), the River Ruhr became increasingly polluted. Over time, using it for recreational purposes became a serious health hazard and bathing was banned due to chemical and microbiological risks. The purpose of the collaborative project “Safe Ruhr” was to verify the current status and to provide a scientific basis for lifting the bathing ban. As the river also provides a raw water source for drinking water production, it was investigated how well the treatment procedures control possible hygienic risks. As study area, the barrier Lake Baldeney was chosen as it embraces earlier bathing sites and tributes to river bank filtration water for drinking water treatment plants. The hygienic condition of the river water was determined over 18 months by measuring general physical, chemical and microbiological water quality parameters including fecal indicators, bacterial obligate and facultative pathogens, parasitic protozoa, enteric viruses and schistosome parasites (Trichobilharzia). Samples were taken at eight locations including sites before and after receiving the discharge of stormwater and treated wastewater, potential future bathing sites and a raw water abstraction point for potable water production. In summary, for all investigated physico-chemical parameters no significant difference between the eight investigated sampling locations on a distinct sampling date were observed. This study focused on hygienically relevant bacteria and parasitic protozoa. Fecal indicators, Escherichia coli, intestinal enterococci and Clostridium perfringens as well as coliform bacteria were detected in 94–100% of the water samples. Enteric pathogens, including Campylobacter spp. and Salmonella enterica, were isolated from 33% and 28% of the samples, respectively, in relatively low concentrations. Among the environmental facultative pathogens, P. aeruginosa was detected at a high frequency of 82% of all samples, but in low numbers, while Aeromonas spp. were found in all water samples in relative high concentrations. The levels of all target organisms were not clearly associated with sources of pollution, with the exception of slightly enhanced numbers of coliform bacteria and E. coli downstream of a sewage discharge point from a wastewater treatment plant. Seasonal variations were observed with higher detection rates of Campylobacter spp. in winter and S. enterica in autumn and winter in contrast to the other bacterial g