Seven typical endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), 4-tert-octylphenol (OP), estrone (E1), estradiol (E2), 17α-estradiol (17α-E2), estriol (E3) and 17α-ethinylestradiol (EE2) in wastewater, were simultaneously determined with gas chromatography-mass spectrometry (GC-MS). Samples, including influents, effluents and wastewater of different unit processes, were taken seasonally from three different sewage treatment plants. The result showed that BPA and EE2 were the two main types of EDCs in all the samples. The average concentration of BPA were in the range of 268.1-2,588.5 ng l⁻¹ in influents and 34.0-3,099.6 ng l⁻¹ in effluents, while EE2 ranging from 133.1 to 403.2 ng l⁻¹ and from 35.3 to 269.1 ng l⁻¹, respectively. Seasonal change of EDCs levels in effluents was obvious between wet season and dry season. Besides, BPA and E3 could be effectively removed by the biological treatment processes (oxidation ditch and A²/O) with the unit removal of 64-91% and 63-100% for each compound, while other five EDCs had moderate or low removal rates. The study also proved that physical treatment processes, including screening, primary sedimentation and pure aeration, had no or little effect on EDCs removal.
The characteristics of ozone decomposition inside the nano-pores of ceramic membranes were identified according to nano-reactor configuration. Three types of ceramic membranes with a pore size of 50 nm were tested with compositions of Al2O3, MnO2/Al2O3 (4%) and CeO2/Al2O3 (4%) respectively. The results showed that the specific decomposition rate of ozone inside membrane pores was 428 times higher than that in pure water outside the pores. The influences of pH values or H2O2 dosages on ozone decomposition in bulk water can be explained on the basis of chain reactions or hydroxyl-radical mechanism; however, these did not work for the behaviours inside the nano-pores of membranes. The extents of the influences of NO3−, SO42− and Ca2+ were even opposite inside to outside the nano-pores of membranes. A unique configuration of nano-reactors within the ceramic membranes tested was proposed based on zeta potentials and water molecule-clusters. Inner charge layer and highly ordered water clusters might play critical roles for the reaction processes inside the nano-reactors.
This study was undertaken to investigate the distribution and variation of microcystins (MC) from a water resource to a water plant in China including long distance transportation, ClO2 preoxidation, coagulation/precipitation, filtration, and disinfection. Advanced treatment methods including ozonation and granular activated carbon (GAC) adsorption were tested to remove microcystins from drinking water. The results indicated that, when containing high level of algae in raw water, preoxidation at 2 mg/L of ClO2 was not enough to stop algae growth in long distance transportation. In the water plant studied, both coagulation and filtration caused significant increase instead of removal of microcystins in drinking water. Chlorine disinfection removed part of microcystins. However, both ozonation and GAC adsorption were able to remove microcystins completely, thereby improving the quality of drinking water in terms of microcystins.
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