An assessment of chemical and physical parameters, several contaminants including metals, and toxicity in the seven major wastewater treatment plants in the state of Aguascalientes, Mexico.

Forty-eight hours acute toxicity tests were employed with Daphnia magna and Lecane quadridentata to assess the influents and effluents of the seven most important wastewater treatment plants (WTP) in the state of Aguascalientes, Mexico, during the 2006 dry and rainy seasons. The WTP of the City of Aguascalientes treated 1948 Ls(-1). The remaining six plants treated wastewater in the range from 28 to 93 Ls(-1).

Implementing Lecane quadridentata acute toxicity tests to assess the toxic effects of selected metals (Al, Fe and Zn).

An environmental study revealed that three metals (Al, Fe and Zn) are common in the San Pedro River (SPR) (Aguascalientes, Mexico). Regrettably, in many samples the concentrations of these metals exceeded the maximum allowed toxicant concentrations levels as defined in by Mexican legislation. The highest concentrations of the three metals were found during the 2005 dry season, with elevated Al concentrations present along the entire river.