The Removal And Transformation Rule Of Some Classic Pharmaceutical Pollutants In DE Oxidation Ditch

Pharmaceuticals are omnipresent in wastewater world-wide recent years，due totheir characteristics of perdurability, bioaccumulation and sluggish biodegradation, theyare also called "fake persistent" pollutants. They have potential and irreversible risk toorganisms and the environment, in spite of their low concentration. As the confluence ofmunicipal sewage and emission source of the treated municipal sewage, the efficiencyof the sewage treatment plants (WWTPs) have direct influence on the water quality ofreceiving water. To study the removal and transformation rule of pharmaceuticalpollutants by WWTPs, the hazard of pharmaceutical pollutants in the effluent ofWWTPs and the removal efficiency of pharmaceutical pollutants by the craft would befurther cleared. The research results would provide valuable theoretical basis for theimprovement of existing sewage purification process, and the elimination ofenvironmental risk coursed by pharmaceutical pollutants.Pharmaceutical pollutants were monitored and analyzed in municipal wastewater thatobtained from one wastewater treatment plant (WWTP) of Xi’an city, which using bothDE oxidation ditch. Based on experimental analysis for five typical pharmaceuticals,solid phase extraction and gas chromatography/mass spectrum (SPE-GC/MS) coupledmethod was established for this research. The accuracy of this method is1.7~9.4ng/L,the extraction agent of SPE is C18, the coefficient of recovery of five selectedcontamination, phenacetin, caffeine, gemfibrozil, naproxen and diclofenac, was73.3%~95%, the relative standard deviation was9.87%~18.0%.Analysis shows that five pharmaceutical pollutants were detected in theinfluent,and the annual average concentrations of phenacetin, caffeine, gemfibrozil,naproxen and diclofenac in influent are15.60μg/l,641.57μg/l,76.1μg/l,15.05μg/l and 22.75μg/l respectively, the concentrations of pharmaceutical pollutants waved greatlyin different seasons. Only phenacetin, gemfibrozil, diclofenac were detected in theeffluent, and all but naproxen were detected in the sludge cake. The research showedthat the DE oxidation ditch had varying degree but not100%removal efficiency ofpharmaceutical pollutants, the un-removed would reenter into the environment assecondary sources, and the WWTPs would change into the main secondary sources.Analysis shows that biodegradation and physical removal contribute mainly to theelimination of them. Phenacetin, diclofenac and gemfibrozil were removed primarilyby physical methods at the rate of61.39%、80.53%、44.37%, then caffeine andnaproxen were reduced mostly by biodegradation at the rate of57.59%、70.83%. Basedon the analysis of biodegradation, it can be concluded that caffeine, naproxen anddiclofenac were more easily degradated in the anaerobic conditions, while phenacetinand gemfibrozil were mainly degradated in the aerobic conditions.