Utilization of microbiotests to assess the contamination of water-bases.

In the present study 4 hazardous wastes originated from 4 different typical industrial activities (leachates of waste oil, waste stockpiles of aluminium factory, sewage of leather industry and of the chemical industry) were examined with several Toxkit microbiotests: the Algaltoxkit, the Protoxkit, the Daphtoxkit and the Thamnotoxkit. The data obtained with the microbiotests were compared to those obtained with the standard conventional acute toxicity tests. The goal of the study was to try out the reproducibility of the tests on the same samples, prepared in the same laboratory and provided to all the participants of the interlaboratory exercise. The first reproducibility evaluation of the tests was made with the reference toxicant potassium dichromate (K2Cr2O7). The outcome was that the lowest coefficients of variation were found at the Thamnotoxkit and highest with Algaltoxkit. The same findings were observed with the industrial waste samples. Different responses were obtained depending on the preparation and the character of the waste. For example, whereas a strong (and highest) toxic effect was found with the Thamnotoxkit, the algal cells in the Algaltoxkit test grew better than in the controls, when exposed to the same waste sample. The sensitivity of the Protoxkit ciliates was the lowest for all the wastes examined. In conclusion of this study, the experience gained and data obtained indicate that the Toxkit microbiotests are suited for routine monitoring after modification of some technical aspects.