Identificación de fracciones tóxicas en efluentes urbanos líquidos

Abstract

The urban wastewater is constituted by discarded water and, as a consequence of the nature and variety of their sources, they constitute a complex combination of chemical substances that interact with each other. Given the particularities of wastewater, it is necessary not only to know their physicochemical characteristics, but also the toxic effects that they can generate in the biota, since the classical approach, through physicochemical analysis, does not consider the interaction between components. Toxicity can be determined by bioassays and, applying a controlled fractionation of the samples and successive bioassays, it is possible to identify which fractions of the effluent contribute to the overall toxicity. Thus, the general objective was to characterize urban wastewater toxicologically and identify the fractions that contribute to global toxicity. A battery of bioassays consisting of D. magna, H, plagiodesmica and T. aestivum seeds was applied, together with a fractionation protocol for the identification of toxic fractions. T. aestivum was not a sensitive indicator for the effluents studied, however, the levels of toxicity indicated for D. magna and H. plagiodesmica indicate that the effluents maintain a considerable toxic content. Fractionation of the samples made it possible to identify suspended solids (>1µm) and nonpolar organic compounds and/or organo-metallic compounds as the fractions that most contribute to global toxicity. The application of the fractionation protocol was effective and generated valuable information of relevance for future studies that allow improving the efficiency of the treatment system. In turn, its usefulness as an evaluation tool for the sustainable management and protection of aquatic ecosystems is manifested.