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2J - TIE (TUP/135) The identification of toxic agent in the tannery wastewater. Tišler, Tatjana1, Zagorc - Končan, Jana2, 1 National Institute of Chemistry, Ljubljana, Slovenia, Slovenia2 University of Ljubljana, Ljubljana, Slovenia, Slovenia ABSTRACT- Effluents are very important sources of mixed chemicals entering aquatic ecosystems. They may contain hundreds, or even thousands of chemicals but only a few of them are responsible for effluents toxicity. The identification and quantification of effluent toxicity is a very important step in wastewater management and for this reason a toxicity test is integrated in modern monitoring programs of effluent quality. In Slovenia, acute toxicity evaluation of effluents discharged into receiving streams is prescribed when toxic substances in the effluent are expected. Acute toxicity with daphnids was determined in the samples of wastewater from tannery industry during regular monitoring of wastewater quality; all investigated samples revealed acute toxicity to daphnids. In the last few samples a significantly higher toxicity was detected. The aim of the investigation was directed towards finding the reason for the increased toxicity of the sample by searching the compound responsible for deterioration of the samples toxicity. An agent for hides disinfection in the technological process of tanning hides was assumed to be a possible reason for the increased wastewater toxicity and thus, the acute and chronic toxicity of the agent to bacteria, algae, daphnids, and fish were investigated. The obtained results revealed high acute and chronic toxicity of the agent to all tested organisms; the highest response to the agent was observed when testing daphnids, the NOEC was detected even at 0.23 ×10-6× v/v % of the agent. We speculated that the investigated agent was the reason for the increased toxicity of the wastewater samples. According to previsions, the toxicity of the samples declined to previous levels following the removal of the toxic agent from the technological process. Key words: disinfection agent, aquatic organisms, tannery wastewater, toxicity |
