TEXTILE WASTE-WATER EFFLUENT TOXICITY IDENTIFICATION EVALUATION

The need to control toxic substances in industrial and municipal waste water effluents has led to the inclusion in National Pollutant Dischar ge Elimination System-(NPDES) per mits of requirements for testing tox icity to aquatic species. Recently, permitted wastewater effluents fro m particular textile dyeing and finishing operations exhibited a low d egree of toxicity to the freshwater Cladoceran Daphnia pulex in acute, static, 48-h testing. An extensive effort was launched to determine c omponents contributing to effluent toxicity. The toxicity identificati on evaluation combined three elements: fractionation of wastewater eff luents, testing for aquatic toxicity, and analyses for specific chemic als. An anionic, speciated form of zinc was implicated as a major cont ributor to the toxicity. Water hardness was a principal determinant of zinc toxicity to Daphnia pulex.