| Pharmaceuticals and personal care products (PPCPs) are a kind of pollutants which consists of prescription, non-prescription pharmaceuticals, sunscreen, detergents, fungicides and spices and so on. As "new" chemicals which have attracted extensive attention by the scientific community and the public since2000, they are closely related to human life. PPCPs have strong biological activity and polarity. Most of them exist in trace concentrations in the environment. They can be detected in the surface water, groundwater, drinking water, soil a, sludge and so on. They bring potential hazard to human health and ecological environment.In this study, carbamazepine (CBZ), bezafibrate (BEZ), ibuprofen (IBP), iomeprol (IOM) and iopromiade (IOP) were chosen as the typical PPCPs in the wastewater treatment plant (WWTP). Firstly, the fast SPE-HPLC dection method was used to determine IOM and IOP in sewage and optimized in the chromatographic and SPE conditions.Five targeted pollutants were detected from each unit in Songjiang wastewater treatment plant of Shanghai by the above established analysis methods. The pattern of transformation was investigated. The results showed that CBZ, BEZ, IBP, IOM and IOP were all found in the WWTP. Before entering the A2/O system, their concentrations in water were high and did not change too much, which showed that the physics processing unit couldn’t reduce them. However, after this process, their amount was significantly decreased, and the five PPCPs were not detected in the sludge except in the aerated grit chamber and the discharge sludge. It proved that the adsorption does not have significant effect on the pollutants removal, and they were mainly removed by biodegradation process. The average removal ratios of compounds were100%for BEZ, IBP, and IOP,79.16%for CBZ, and36.69%for IOM respectively. Then, the returned sludge in Songjing WWTP was collected and used to carry out the sludge adsorption experiments. The influence of pH, temperature and pollutants’ concentration on the adsorption was studied. The results showed that IOM and IOP could hardly be adsorbed. Through the study of the influencing factors, CBZ was adsorpted on the sludge easily in the neutral conditions, BEZ and IBP had better adsorption phenomena under the acid and alkali conditions. And when the concentration of CBZ and IBP were low, the higher was the temperature, the adsorption was smaller, while it was on the contrary for BEZ. Through the simulation of kinetic model, the pseudo two-order was better than the pseudo first-order model, it could be concluded that the adsorption was carried out by forming chemical bond as the electronic transfer or exchange between sludge and pollutants. After the simulation of Henry, Freundlich and Langmuir adsorption isothermal equation, it was found that the adsorption of CBZ, BEZ and IBP happened with both chemical and physical adsorption. Based on the study of the thermodynamic parameters of the adsorption process, it was indicated that for the CBZ and IBP it was a spontaneous exothermic process, but for BEZ it was spontaneous and endothermic.Finally, the returned sludge in Songjing WWTP was collected to carry out the aerobic biodegradation experiments. The MLSS was maintained between3000-5000mg/L, DO was2-4mg/L, pH was7-8. The PPCPs were added in the reacter to study their degradation. The results showed that, CBZ can not be removed in both the bulking and the normal state, while IOM and IOP can be degraded completely in the two states. For BEZ and IBP, they could be degraded in the normal state but the bulking could not degrade them. Through the single pollutant biodegradation experiments and LC-MS analysis, the possible degradation mechanisms of BEZ, IBP, IOM and IOP were explored. It was found that these pollutants were removed through form small molecule compounds with the metabolism of the microorganism. |
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