Evaluation of toxicity, genotoxicity and environmental risk of simulated textile and tannery wastewaters with a battery of biotests

Textile and tannery wastewaters are complex mixtures of toxic pollutants and only a battery of ecotoxicity tests can assess their potential environmental impact and the actual effectiveness of alternative treatments. In this work the toxicity of four simulated textile and tannery wastewaters was evaluated by means of a battery of seven bioassays, using organisms that belong to different trophic levels. Moreover, since the outputs of the bioassay battery were quite difficult to compare, a novel synthetic index for environmental risk assessment was applied to the outputs of the test battery. All four simulated wastewaters were very toxic but they showed no mutagenic effect. The alga Pseudokirchneriella subcapitata was the most sensitive organism. In addition, the use of two mathematical models pointed out the interaction effect between dyes and salts, which resulted in a synergistic effect of wastewater toxicity.