Distribution and Removal of Endocrine-Disrupting Chemicals in Industrial Wastewater Treatment

In the present work, the distribution of endocrine-disrupting chemicals (EDCs) in an industrial (denim-dyeing) wastewater and pollutant removal efficiencies of three processes from two treatment plants were studied. Result indicated that nonylphenol (NP) was the main pollutant in the wastewater with concentrations of 30-400 mu g/L, followed by bisphenol A (BPA) with concentrations of 0.37-14.5 mu g/L, while only a trace amount of triclosan (TCS) was detected. High pH values and high dye concentrations had no effect on treatment efficiencies of all processing units. Conventional activated sludge treatment process showed the highest removal efficiencies of 90% for NP, 92% for BPA, and 94% for TCS. Performance of oxidation ditch treatment process was inferior to conventional sludge system for reduction of NP. The acid sedimentation unit could remove nearly half of NP and TCS from the influent, while an increasing trend was observed in the same unit for the concentration of BPA, which might be caused by transformation of unidentified parent chemicals in the raw wastewater. The long hydraulic retention time of the sedimentation unit did not favor reduction of NP and might influence the removal efficiency of other two compounds. To reduce effluent endocrine effects to the aquatic organisms, efforts should be focused on NP and its parent compounds.