Bioassay of treated color wastewater with Electro Fenton by Daphnia Magna

The contamination of water resources resulting from industrial output discharge is a serious threat to the water-living organisms. Chemical and physical examinations are not enough to evaluate the potential effects of these pollutants on aquatic life. Biological tests can provide appropriate and direct measure of toxicity as a complete physicochemical criterion of wastewater quality. The requierd Daphnia was provided in fish breeding centers of Esfahan and after preparing different concentrations of raw wastewater and decolorated samples in eight percent of the differents volume, 10 Daphnia was added to all containers containing samples of raw wastewater, decolorated and control samples rinsed with diluted water. All samples were observed after 48 hours and the number of dead animals in each test container was counted. In the final experiments, acute toxicity units, LC50 - 48h and efficiency of toxicity removal on the optimum conditions of Electro Fenton process were calculated. Based on the results of toxicity tests it was determined that LC50 - 48h in synthetic wastewater samples with dye concentration in 40mg/L increased from 18% before decoloration reached 70% after decoloration, samples of wastewater synthetic concentrations dye 100 mg/L from 14 to 50%, wastewater synthetic with concentrations dye of 200mg/L from 10 to 35 % and in samples containing of 300 mg/L the dye concentrations of 6.8 reached 20 % respectively. The efficiency of toxicity removal for different dye concentrations reached 76, 72, 71 and 66 % respectively. According to the results obtained, it can be stated that to evaluate the potential toxicity of colored wastewaters discharged into surface waters and to determine the quality criteria for contaminant permissible concentrations, bioassay is a simple, quick and effective procedure.