Toxicity evaluations of wastewaters in Austria with conventional and cost-effective bioassays

The acute toxicity of 42 samples of different types of domestic and industrial discharges was assessed with a battery of tests comprising the standard Daphnia magna bioassay and three cost-effective new microbiotests (cyst-based Toxkits): the Rotoxkit F with the freshwater rotifer Brachionus calyciflorus and the Streptoxkit F and Thamnotoxkit F tests with the freshwater fairy shrimps Streptocephalus proboscideus and Thamnocephalus platyurus, respectively. Chemical analyses were performed for conventional water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD5), NO2, NH3, NH4+, O2, and pH. Toxicity of the samples, expressed as German regulatory G-values, was found to vary between 1 and 128. The results of these toxicity tests indicate that the Toxkit bioassays were as sensitive as the D. magna acute test. The crustacean T. platyurus was in 75% of the toxic samples more sensitive than D. magna. Relationships between the chemical composition and the toxicity of the discharges could be established in some cases, but not in others, which confirms the difficulties of extrapolating toxic hazards of complex wastes from (mostly restricted) chemical analyses. This study demonstrates the potential of cost-effective bioassays (such as, e.g., cyst-based Toxkits) as attractive alternatives to (expensive) conventional bioassays for routine monitoring of effluents and wastes.