The Distribution And Transfer-transformation Rule Of Pharmaceutical Pollutants In A Wastewater Treatment Plant Of Xi'an City

Pharmaceutical pollutants were monitored and analyzed in municipal wastewater that obtained from one wastewater treatment plant (WWTP) of Xi'an city, which using both A~2/O process and Medium load process to treat wastewater separately. Based on experimental analysis for nine typical pharmaceuticals, solid phase extraction and gas chromatography/mass spectrum (SPE-GC/MS) coupled method was established in this disseration The distribution and transfer-transformation rule of pharmaceutical pollutants in the wastewater were studied and the removal efficiencies of the pharmaceuticals by two different processes were compared and summarized.It was concluded that recovery rates of nine pharmaceutical pollutants were at 73.3%-97.7%, and relative standard deviation (RSD) were at 8.9%-20.4%, and the method detection limit of the target compounds were at 1.7-9.4 ng/L that using C18 as the extractant agent to SPE in experiment. The concentrations and types of nine pharmaceutical pollutants had large changes in the wastewater of the WWTP, and the determination results showed that nine typical pharmaceutical pollutants named caffeine, bezafibrate, cholesterol, phenacetin, aminopyrine, diclofenac acid, clofibrate acid, gemfibrozi and naproxen, were found in the influent and their annual average concentrations were 27.79μg/L, 12.75μg/L, 11.634μg/L, 7.65μg/L, 3.59μg/L, 1.48μg/L, 0.61μg/L, 0.49μg/L and 0.39μg/L respectively. Their treated concentrations in the effluent were at 80-540ng/L. Aminopyrine, diclofenac acid, gemfibrozi, clofibrate acid were easier to be removed in A~2/O process than in medium load process. Phenacetin, cholesterol and bezafibrate were more suitable to be degraded in the process of medium load with aerobic bacteria. The removal of nine pharmaceutical pollutants in the primary sedimentation tank and aeration tank reached 70%, and the removal efficiencies were better while the concentrations in the influent were higher.The sludges of both A~2/O process and medium load process had obvious adsorption effect for nine typical pharmaceuticals, especially for caffeine at the concentration of 1.973μg/g in A~2/O process, and 1.7μg/g in medium load process. The sludge in A~2/O process had good adsorption capacities for aminopyrine, gemfibrozi and naproxen. Medium load process sludge had better adsorption for diclofenac acid and clofibrate acid than that in A~2/O process. The removal proportion of pharmaceutical pollutants in the sludge was less than 10%, and physico-chemical removal only about 30%, and biodegradation was about 70 %.