(565d) Studies on Evaluation of Acute Toxicity Factor for Selected Industrial Effluents Using Zebra Fish(Danio Rerio) As a Test Organism

 Man in his attempt to lead a comfortable life, extracts all the resources from mother earth. In this process of utilization of useful materials he lets into the environment many hazardous substances, unaware of their effect on his own life. The rate of discharge of these materials into the ecosystem is more than that of their degradation by natural process, resulting in the accumulation of such substance in the environment. Accordingly the environment in the 21^st century is becoming increasingly polluted; mainly water pollution has become a major threat to the existence of living organisms in aquatic environment. A huge quantity of pollutants in the form of domestic, agricultural run offs and industrial effluents are discharged directly or indirectly into the water bodies, which has severe impact on its biotic and abiotic environment. Before discharge of waste waters/effluents into the recipient, it is necessary to purify them with adequate treatment in a way and to an extent that does not threaten natural process and does not reduce the possibilities of their multi-functional use.

            The aim of this study is to ascertain performance evaluation of Effluent Treatment Plants (ETP) of three different industries namely Steel sector, Pharma sector and Power sector with special reference to toxicity reduction using Zebra Fish as test organism.  The 48-hrs acute toxicity factor T_F was introduced by the statutory authorities in India, for evaluation of industrial effluents and wastewaters is a number on geometrical scale by which the samples need to be diluted to ensure hundred percent survivals of fish under specified conditions. This bio-assay test can be considered as useful analytical tool for screening of chemical analysis and early warning system to monitor the different operational units of wastewater treatment plants. To evaluate the 48-hrs acute toxicity factor T_F, samples were taken from different operation units of ETP which includes physico-chemical units & biological unit, etc. This evaluation showed that improvements are still needed to increase their efficiencies for treating effluents. The results clearly indicate that, bio assay tests provide additional information on the toxicity potential of industrial effluent discharges and effectiveness of existing effluent treatment techniques in reduction of toxicity. So results of the present study clearly showed that physico-chemical parameters alone were not sufficient in obtaining reliable information on treated wastewater toxicity and that toxicity tests must be performed in order to guarantee the safety of aquatic organisms along with the pubic expectations. The combined use of toxicity and chemical parameters appears to be need in the quality control of wastewaters.

Key Words: Effluent Treatment Plant (ETP), Zebra Fish, Acute Toxicity Factor (T_F), Treatment Efficiency, etc.