Evaluation of wastewater effluents by small-scale biotests and a fractionation procedure

Municipal and industrial effluents were screened with a battery of biotests and with a modified toxicity identification evaluation Phase I procedure. The acute toxicities of the effluent samples were low and the submitochondrial reverse electron-transport (RET) test was the most sensitive toxicity test. Estrogenic effects were found in almost all effluent samples, and genotoxicity was detected in one concentrated effluent sample. The fractionation methods we used proved to be especially effective at tracking toxicity caused by metals and organic contaminants, with the RET test being particularly suited to evaluating pH-dependent toxicity. The used solid-phase extraction columns with both hydrophilic and hydrophobic binding properties turned out to be suitable for removing or reducing organic toxicity-causing substances from the effluent samples. The results of this study show that the use of only conventional acute toxicity tests for effluent assessment will not be sufficient—the genotoxic, hormonal, and even bioaccumulative potential of the effluents and effluent fractions should be evaluated as well.