Removal Of Pharmaceuticals And Personal Care Products By Membrane Bioreactor And The Influence Of Solid Retention Time

Research on removal of micro-pollutants by membrane bioreactor (MBR) is needed to ensure the safety of MBR effluent and can be helpful in exploring utilization of MBR in the wastewater reclaimation process. 10 pharmaceuticals and personal care products (PPCPs) were selected as representatives of micro-pollutants in this thesis. Removal efficiency and pathway of these PPCPs by MBR were studied. The solids rention time (SRT) of MBR was changed in order to find its influence on PPCPs removal. Furthermore, batch experiments were taken to analysis the removal pathway.To evaluate the removal of PPCPs by MBR, a MBR and a sequencing batch reactor (SBR) were operated under the same condition.The results showed that MBR was more efficient in the safty and stablity of the effluence. There was no significant difference between the two bioreactors on the removal of Trimethoprim and Erythromycin. However,The MBRs exhibited greater elimination rates for other selected PPCPs, especially Caffeine,Ketoprofen and DEET . Research on transfer pathway of PPCPs revealed that neither membrane in the MBR nor sedimentation process in the SBR can removal the targets obviously. But the membrane can withhold some investigated substances that absorted to the colloid particles. The main removal pathways of the selected substances in MBR and SBR were both biodegradion, the study on sludge-water partition coefficient (Kd) of PPCPs showed the relative intensity of sludge adsorption.Batch experiments were conducted to analysis the mechanism of the selected PPCPs's removal.The results showed that the mechanism for their transfer and variation was basinally biodegradation.The sludge adsorption contributed little to the removal of Erythromycin and Carbamazepine while other targets can be adsorbed partially. The proportion of Ketoprofen,DEET and Caffeine that were adsorbed by sludge was about 20% while the proportion of Diclofenac and Clofibric acid was about 15%.The MBRs were operated at 4 different SRTs (5d, 10d, 20d, 40d) to evaluate the SRT's impact.The results showed that neither Sulpiride nor Carbamazepine can be eliminated effectively,the removal of Metoprolol and DEET was not relative with SRT,and the removal rates of the two substances were 50% and 80% respectively. The removal rates of Caffeine,Ketoprofen and Trimethoprim increased with longer SRTs slowly,the increasing range is about 10%. Clofibric acid and Diclofenac were best eliminated at SRT=20d. Erythromycin were removed better when the SRT increased obviously, the range is from blow 70% when SRT=5d to above 90% when SRT=40d.