Impact assessment of a wastewater treatment plant effluent using instream invertebrates and the Ceriodaphnia dubia chronic toxicity test

• Published in: Water research (Oxford) 1999, Vol.33 (1), p.266-278
• Main Authors: KOSMALA, A, CHARVET, S, ROGER, M.-C, FAESSEL, B
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Ceriodaphnia dubia; Continental surface waters; Earth sciences; Earth, ocean, space; Ecotoxicology, biological effects of pollution; Engineering and environment geology. Geothermics; Environmental Sciences; Exact sciences and technology; Fresh water environment; Freshwater; Fundamental and applied biological sciences. Psychology; Natural water pollution; Pollution; Pollution, environment geology; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(98)00176-6

The purpose of this study was to assess the specific impact of a wastewater treatment plant (WWTP) effluent on the receiving water. A combination of a field survey and laboratory toxicity tests was used to detect a possible cause-effect relationship between the plant discharge and the receiving water quality. In addition to biological and chemical quality of the river upstream and downstream from the WWTP outfall, we assessed Hydropsychid life cycle as a field bio-indicator. Laboratory experiments were carried out using the 7-day Ceriodaphnia dubia chronic toxicity test. Field and laboratory studies were performed simultaneously almost every month from March 1995 to February 1996. Throughout the year, we observed a biological degradation at downstream site compared to upstream site based on biological indices, while we detected a constant chronic toxicity from C. dubia test. Field and laboratory indicators showed that the effect of the WWTP effluent on organisms was at its highest in summer. By studying both the effluent and the receiving water, we showed that not only the concentration of the effluent in the river but also its quality explain the impact of the WWTP effluent in summer. Thanks to field investigation, we detected the impact of the WWTP above the outfall, the WWTP upstream site being polluted by the stormwater overflow. Disturbances described were due to nutrient loading from the organic matter and to micropollutants contained in the WWTP effluent.