Occurrence and removal efficiencies of eight EDCs and estrogenicity in a STP

The occurrence and removal of eight endocrine disrupting compounds (EDCs), including estrone (E-1), 17 beta-estradiol (E-2), estriol (E-3), 17 alpha-ethinylestradiol (EE2), diethylstilbestrol (DES), bisphenol A (BPA), nonylphenol (NP) and octylphenol (OP), and their estrogenicities were investigated in a sewage treatment plant in Harbin city, China. The EDCs were extracted from wastewater samples by solid phase extraction (SPE) method and analyzed with gas chromatography coupled with mass spectrometry (GC-MS). The average concentrations in the influents and effluents ranged from 6.3 (EE2) to 1725.8 ng L-1 (NP) and from <LOD (EE2) to 368.5 ng L-1 (NP), respectively. The mean removal efficiencies were in the range of 16.9 (DES) to 94.4% (E-3). 6.4-46.1% of EDCs were removed during the primary treatment, and the adsorption on solid particles was assumed as the dominant removal mechanism. The removal efficiencies in anoxic and aerobic biological treatment units ranged from -30.2% to 62.2% and from -8.3% to 83%. The yeast estrogen screen (YES) was used to analyze the estrogenicity of the test samples. The EEQ in the influents and effluents were in the range of 21.7-54.7 ng L-1 and 3.5-29.6 ng L-1, respectively. The overall EEQ removal efficiencies were in the range of 15.6-92.8%, and the biological treatment was crucial to EEQ removal. The total estrogenicity increased after primary treatment which might be owing to the deconjugating of estrogen compounds by microbial activity. The EEQ value based on chemical substrates calculation was larger than the results of the YES assay, with a ratio value of 3.94 +/- 4.00 in all water samples.