Monitoring of a water treatment plant using acute toxicity tests with the cladoceran Daphnia magna and the freshwater rotifer Lecane quadridentata

Background. Monitoring of physicochemical parameters and acute toxicity tests allow us to measure water quality of the influent and effluent of wastewater treatment plants in accordance with the parameters established by the NOM-003-SEMARNAT-1997. Goals. We measured water quality of the influent and effluent of the wastewater treatment plant of the Autonomous University of Aguascalientes during 2007-2008. Methods. Every 15 days physicochemical parameters were taken and acute toxicity tests were conducted with the cladoceran Daphnia magna and the rotifer Lecane quadridentata. Results. The influent showed median lethal concentration to be between 25.71 and 3.88 toxic units with L. quadridentata, while with D. magna the median lethal concentration was between 31.51 and 3.17 toxic units. The effluent showed median lethal concentration to be between 60.71 and 1.64 toxic units with L. quadridentata, whereas the D. magna showed no toxicity. Conclusions. We concluded that the wastewater treatment plant of the Autonomous University of Aguascalientes in 2007-2008 fulfilled Mexico's water quality criteria after treatment.