Assessment of the Microbiological Quality of the River Tisa in Serbia - page 04



The values for all investigated groups of bacteria in the river water showed a great variability, which can be attributed to unequal loading with wastewater during the sampling seasons. The results obtained in our investigation show a high initial organic load of industrial and municipal wastewater, followed by an abrupt increase in the organotrophic bacteria and faecal coliform counts. In this study, pollution was found along the Serbian stretch of the River Tisa, while previous investigation indicated pollution of similar proportions along the upstream Hungarian stretch (Teszarne et al., 2003).

Contamination of surface water with coliform bacteria indicates an inadequate treatment of wastewater and requires an immediate investigation into its cause, following risk assessment, appropriate and immediate measures. In the case of surface water contamination, the origin has to be clarified, whether such contamination is weather-related or was caused by anthropogenic sources such as wastewater discharge. Total coliforms indicated II and III classes of water quality, while faecal coliforms indicated III and IV classes. Faecal coliforms to Enterococci ratio indicated a human origin of the pollution. The origin of the microbiological pollution can be attributed mainly to a large amount of raw or improperly treated urban wastewater.

According to the obtained results for organic load assessment, the River Tisa water quality was in the range of II to III class, with a satisfactory level of self-purification. Similar results were obtained during previous investigations (Gajin et al., 1989; Matavulj et al., 1989). The origin of organic pollution in an ecosystem can be attributed to organic manure, fertilizers, high stocking density, feed waste, faecal matter, algal bloom and human interference (Lloberra et al., 1991; Moriarty, 1997).




The microbiological pollution detected at selected sites can be attributed mainly to a large amount of raw or improperly treated urban wastewater,, while increased agricultural activity in this area during the sampling period probably contributed to the detected organic pollution. Stricter law regulations on effluent discharge from aquaculture facilities would give incentive to this industry to reduce effluent volumes and organic loads.

In order to take appropriate measures which would result in acceptable river water quality and compliance with national and international quality standards and directives, a more profound knowledge of microbial pollution in aquatic environments is essential.



Although the microbiological evaluation of water quality is not recommended as a routine procedure by the national Law on Water (’’Official Gazette of RS’’, number 46/91, 53/93, 67/93, 48/94, 54/96), we believe that routine microbiological analyses of water quality, as required in compliance with EU Directives (EU-Bathing Water Quality Directive 2006/7/EEC), would be a necessary and important standard for evaluating the quality of water intended for human consumption. In compliance with the EU Directive, Serbia’s regulations should specify the frequency of source water sampling, sampling and analysis methods, the scope of microbiological analysis and the acceptable limits for the target microorganisms in water samples, especially for microbes that cause disease not only by ingestion, but also by inhalation and contact. The present study concludes that proper water quality management and continuous monitoring of benthic microbes are the key factors to reduce the bacterial load and ultimately reduce the likelihood of disease outbreak.