Paper review ----EDCs

Endocrine Disrupting Chemicals (EDCs) is a kind of widely-existed micro-contaminants in the Environment that can have adverse impacts on the endocrine system of humans and animals. Currently, the occurrence and increasingly frequent detection of EDCs in water resources around the world is a growing concern. In 2001, the Stockholm Convention under the auspices of United Nation Environmental Program, specified a suite of persistent organic chemicals considered as potential endocrine disrupting chemicals (EDCs) in the environment (UNEP, 2001)[1]. A wide range of chemical compounds have been found to be capable of disrupting the endocrine systems since then.For instance, steroid estrogenic compounds are globally detected in river, sea, and their sediments, and even in underground water [2,3,4]. Natural and synthetic estrogens have been reported in US wastewater since the 1960. However, these hormones did not become widely recognized contaminants until their occurrence in wastewater effluents was linked to reproductive impacts in fish. Previous studies also show that municipal sewage is the most important source of EDCs in natural water, so that effective treatment processes are critical for minimizing the concentration of EDCs in the environment. Ozonation is one of the most promising methods, which in this paper we will discuss.Esplugas[5] explained in his review article that advanced oxidation processes (AOPs) are appropriate to oxidize EDCs and ozonation gave good expectations to be applied with success in water industry. In his opinion, techniques for treating micro-pollutants are very diverse and frequently one or more treatment techniques are required to degrade these compounds. Conventional process like activated sludgebiological treatment can not completely remove micro-pollutants by itself, so that to achieve target removal goal combined techniques are required, such as filtration, activated carbon adsorption, reverse osmosis, chlorine or ozone oxidation, and membrane technology. Based on previous studies, he also concluded that both dark oxidation method like ozonation and light oxidation processes like UV/H2O2 can remove more than 90% of the most target compounds, while light oxidation seems to be a better option for application because its TOC (total organic carbon, which stands for the overall contaminant concentration) removal efficiency is higher.Nakada developed a combined technique of ozonation and sand filtration with activated sludge that gave efficient removal higher than 80% of most target compounds[6]. Tsuno used a new advanced treatment system to treat EDCs, which consists of biological nutrient removal process combined with reduction of excess sludge by ozonation and phosphorus recovery by crystallization and polishing-up ozonation process[7]. And his results are that general performance is not affected by any additional process, EDCs removal efficiency increased by 90%, and energy consumption reduced by 40%. Nakada and Tsuno both use the activated sludge process in their combined method for EDCs treatment, and they overlook the environment risks of EDCs-containing sludge residual, which is a major concern that Esplugas brought about in his review article.Yue made evaluations of pilot-scale oxidation of several EDCa during drinking water ozonation treatmen[8]. He studied the affecting factors of EDCs removed by ozonation treatment process. His major conclusions are: ozonation effectivelytransformed EDCs with high reaction rate with molecular ozone, and the oxidation efficiencies exceeding95% were observed for these high reaction rate EDCs. Oxidation effic iencies were quite variable for EDCs with low to moderate reaction rate with molecular ozone. He put forward an innovative classification of EDCs based on reaction rate with molecular ozone, which can serve as an important source for future study in this area.To sum up, in these studies, most of the target compounds investigated reacted quickly with ozone, so that ozonation systems are promising for efficient removal of some EDCs. A more thorough research regarding EDCs removed by ozonation is needed before it is applied in water industry and helps reducing the environmental risks of EDCs in natural water.References[1] UNEP. Stockholm Convention on Persistent Organic Pollutants. Stockholm: UnitedNation Environmental Program; 2001.[2] Lai K M, Scrimshaw M D, Lester J N. Prediction of the bioaccumulation factors and bodyburden of natural and synthetic estrogens in aquatic organisms in the river systems. Sci.Total Environ. , 2002, 289: 159-168.[3] Baronti C, Curini R, D’Ascenzo A, et al. Monitoring natural and synthetic estrogens atactivated sludge sewage treatment plants and in a receiving river water. Environ. Sci.Technol., 2000, 34: 5059-5066.[4] Fine D D, Breidenbach G P, Pricec T L, et al. Quantitation of estrogens in ground waterand swine lagoon samples using solid-phase extraction, pentafluorobenzyl/ trimethylsilyl derivatizations and gas chromatography–negative ion chemical ionization tandem mass spectrometry. J. Chromatogr. A , 2003, 1017: 167-185.[5] Santiago Esplugas, Daniele M. Bila, Luiz Gustavo T. Krause, M´arcia Dezotti.Ozonation and advanced oxidation technologies to remove endocrine disruptingchemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) in water effluents. Journal of Hazardous Materials, 2007, 149, 631–642.[6] Norihide Nakada, Hiroyuki Shinohara, Ayako Murata, Kentaro Kiri,Satoshi Managaki,Nobuyuki Sato, Hideshige Takada. Removal of selected pharmaceuticals andpersonal care products (PPCPs) and endocrine-disrupting chemicals (EDCs) during sand filtration and ozonation at a municipal sewage treatment plant.Water Research, 2007, 41, 4373 – 4382.[7] HiroshiTsuno, Kiyomi Arakawa, Yasuhiro Kato, and HideakiNagare. Advanced SewageTreatment with Ozone Under Excess Sludge Reduction, Disinfection and Removalof EDCs. Ozone: Science and Engineering, 2008, 30:238–245[8] Chaoyang Yue,Rajesh Seth,Shahram Tabe,Xiaoming Zhao,Chunyan Hao,PaulYang,LindaSchweitzerand TaherJamal. Evaluation of pilot-scale oxidation of several PPCPs / EDCs (pharmaceuticals and personalcare products/endocrine disrupting compounds) during drinking water ozonation treatment. Water Science and Technology, 2009, 9.5,577-582.。