Removal Efficiency Of Antibiotics And Environmental Hormones And Their Inhibition On The Performance Of Activated Sludge In A~2/O Process

Because the anaerobic anoxic aerobic（A²/O）sewage treatment process has the ability to degrade organic matter and remove nitrogen and phosphorus,it has become the most widely used process in municipal sewage treatment plants.With the abuse of pharmaceuticals in recent years,two kinds of emerging contaminants,antibiotics and environmental hormones,have gradually appeared in the tail water of A²/O sewage treatment plant.Because A²/O sewage treatment process is initially aimed at removing conventional pollutants,and the removal effect of two kinds of emerging contaminants,antibiotics and environmental hormones,is unknown.Therefore,this study studies the distribution of conventional pollutants,antibiotics and environmental hormones in A²/O sewage treatment plant in different seasons.At the same time,A²/O pilot plant is established to study the influence of important parameters of A²/O process on the removal of antibiotics and environmental hormones,select the best working condition,and finally study the inhibition effect of single antibiotics and environmental hormones on activated sludge in A²/O system.The main results are as follows:（1）The distribution characteristics of antibiotics and environmental hormones in A²/O sewage treatment plant were studied.The effect of seasonal difference on the removal effect of antibiotics and environmental hormones in A²/O sewage treatment plant was studied.The results showed that the concentration of antibiotics and environmental hormones in the influent of A²/O sewage treatment plant in winter was generally higher than that in spring,and the removal effect of antibiotics and environmental hormones in winter was higher than that in spring.The changes of antibiotics and environmental hormones after each treatment unit of A²/O sewage treatment plant are studied.The results show that A²/O unit is an important unit to remove antibiotics and environmental hormones.（2）Through the establishment of A²/O pilot plant,the effects of key parameters of A²/O process on the removal of antibiotics and environmental hormones are studied.The optimized parameters are hydraulic retention time（HRT）for 24 h,dissolved oxygen（DO）for 2 mg/L and sludge concentration（MLSS）for 5000 mg/L.The effect of initial concentration of antibiotics and environmental hormones on the performance of A²/O system was studied.When the concentration of antibiotics and environmental hormones was high（1 mg/L）,the removal effect of A²/O system on conventional pollutants was significantly inhibited,while the removal effects of norfloxacin（nor）,roxithromycin（ROX）,sulfamethoxazole（SMX）and bis（2-ethylhexyl）phthalate（DEHP）were increased by 13.4%,4.3%,0.9%and 5.0%respectively.（3）The inhibitory effects of different single antibiotics and environmental hormones on activated sludge in A²/O system were studied.In the study of antibiotic inhibition effect,ROX,SMX and oxytetracycline（OTC）have strong inhibition effect on anaerobic sludge.The removal rates of NO₃^--N and cod were 0.6%and 4.74%,10.8%and 3.6%,respectively.Antibiotics had no significant inhibitory effect on the removal of NH₄⁺-N by aerobic sludge;In the study of the inhibitory effect of environmental hormones,DEHP has the strongest inhibitory effect on anaerobic sludge,and its removal effect on COD is only 5.6%.Estrone（E1）and bisphenol A（BPA）have strong inhibitory effects on anoxic sludge.Environmental hormones had no significant inhibitory effect on the removal of NH₄⁺-N by aerobic sludge.（4）The results showed that with the increase of the initial concentration of antibiotics and environmental hormones,the relative abundance of Proteobacteria,Bacteroidetes and Actinobacteria in anaerobic and anoxic sludge decreased to 42.08%and 48.09%,9.60%and 9.62%,13.90%and 5.48%,respectively,The relative abundance of Chloroflex and Nitrospirae in aerobic sludge will also show a downward trend,falling to 0.95%and 0.53%respectively.