Fate And Occurrence Of Endocrine Disrupting Chemicals In Urban Aquatic Environment And The Control By Permanganate Oxidation

Endocrine disrupting chemicals (EDCs) is a kind of ubiquitous micropollutants that will elicit adverse effects on endocrine systems of human and wildlife. The study of them in urban aquatic environment will have great significance for protecting human health and may shed light on how to efficiently control them in drinking water treatment processes.Thirteen kinds of frequently detected EDCs were selected as target compounds in the present study, including 5 kinds of estrogens, 4 kinds of phthalate acid esters (PAEs), bisphenol A (BPA) and 3 kinds of alkylphenols (APs). Solid phase extraction was employed for aqueous sample processing. Solid samples were freeze-dried and treated by ultrasound-assisted solvent extraction. Target compounds were determined by high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS). Yeast two-hybrid system was used to investigate the estrogenic activities of water samples.Wastewater is the main source of EDCs in surface and drinking waters. Studies were therefore first focused on a sewage treatment plant (STP) of Harbin. Results indicate that the removal efficiencies of EDCs range from 70% to 96% in the STP, but not for 17α-ethynylestradiol (EE2) (60.4%) and diethylstilbestrol (DES) (51.3%). The removal rates of estrogenicity are 58.1%-84.3%. The secondary treatment process plays a dominant role for the removal of EDCs in the STP. Whereas the primary sedimentation treatment has a very limited performance for them, in which the concentrations of estriol (E3), estrone (E1), dimethyl phthalate (DMP) and 4-t-octylphenol (OP) are increased in its effluent comparing to those in its influent. Similar situation is also happened to estrogenicities in it. Results also indicate that almost all EDCs'partition coefficients (Dp) between liquid and solid phases have been observed to have a negative relationship with suspended solids (SS) and dissolved organic carbon (DOC). While the effect of octanol/water partition coefficient (Kow) on Dp is minimal. The mass balance was carried out for evaluating the ability of the secondary treatment process to remove EDCs. It turns out that the removals obtained from biodegradation range from 4.2% (EE2) to 91.8% (DMP) and 74.4% for estrogenicity. In the meantime, the removals achieved by excess activated sludge range from 0.5% (BPA) to 45.2% (EE2) and 1.1% for estrogenicity. The residual of EDCs (7.0%-68.6%) and estrogenicity (24.5%) are entered into Songhua River water with the effluent of secondary sedimentation.Thus, the EDCs contained in untreated or incomplete treated wastewater may travel along the water path from STPs to surface waters including raw water used for drinking water production. Results from the investigation of EDCs in Songhua River water show that the concentrations of five kinds of estrogens are rather high over the Harbin reach, with the maximum concentration of 49ng/L. Four of PAEs are more abundant than others, especially dibutyl phthalate (DBP) which has a highest concentration of 263μg/L. The concentrations of three kinds of APs are in the range of 56-1 505ng/L. The concentrations of BPA are relatively stable in the range of 30-150ng/L. The estrogenic activities of Songhua River water in summer and autumn are 528-965pg/L of estradiol equivalents (EEQs), and the estrogenic activities of source water are in a high level in summer.Drinking water was contaminated by EDCs due to the contamination of source water. Results indicate that the coagulation-sedimentation process plays a dominant role in the removal of EDCs and estrogenicity in a waterworks of Harbin. Processes of sand filtration and chlorination are unstable, and the estrogenicities of their effluents sometimes are higher than those in their influents. The total removal rates of estrogenicity in the plant are 34.6%-50.5%. The concentrations of most EDCs left in the effluent of the plant are increased after pipe delivering. The estrogenic activities of tap water are increased to the maximum of 44.9% in comparison with those of the effluent of the plant. It verifies that EDCs in drinking water partly come from the secondary contamination produced in the process of pipe delivering besides the contaminated source water. Results also show that almost all typical EDCs are present in tap water of Harbin except steroid estrogens. The concentration of DBP is the highest one among these EDCs in tap water. The estrogenicities of tap water of Harbin are 347-1 362pg/L of EEQs measured in seven sampling events.For the low performance of traditional water treatment processes, permanganate was therefore used as an oxidant to control phenolic estrogenic EDCs. It was found that the reaction between permanganate and phenolic EDCs is second-order overall and first-order with respect to both reactants. The rate constants are increased exponentially with the increase of temperature, while decreased first with the increase of pH and then increased with the increase of pH. The higher the pH value in alkaline conditions, the faster the reaction is. The reaction between phenolic EDCs and permanganate is faster in natural water background than that in ultra-pure water system. Results also show that the degradation of phenolic EDCs was greatly promoted in the presence of reductives, including humic acid, Mn2+, Fe2+, NO2ˉ, SO32ˉ, EDTA, citrate and oxalate. Among them, the most efficient one is humic acid. However, the promotion of permanganate oxidation induced by the presence of reductives takes effect under acidic and neutral pH conditions, while the effect of pH plays a dominant role under alkaline conditions. By means of spectrum scan, it is proposed that these reductives may act as initiating agents of permanganate transformation into reactive manganese intermediates being mainly Mn(V) that may be responsible for the observed enhanced oxidation effects. Variation of estrogenicity was also investigated during the oxidation of E1 with permanganate. Results show that the estrogenicity is increased in the initial reaction phase and then decreased fastly. Permanganate oxidation is therefore a feasible option for control of phenolic EDCs and their estrogenicities in water treatment. However, the contact time must be enough in order to remove them without causing the increase of estrogenicity.