Removal of Environmental Hormones and Pharmaceuticals from WWTP Sewage by a Novel Electromembrane Process

• Main Authors: Wan-ying Shen, 沈宛瑩
• Other Authors: Gordon C. C. Yang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/75303521550021010528

碩士 === 國立中山大學 === 環境工程研究所 === 101 === In recent years, many studies have indicated that wastewater treatment plants (WWTPs) are incapable of removing emerging contaminants (e.g., caffeine and bisphenol A) effectively. Wastewater recycling increases the opportunity of emerging contaminants introduced into the drinking water systems and thus human exposure to emerging contaminants has escalated. The objectives of this research are three-fold: (1) to investigate the concentration variations and transport/spreading of pharmaceuticals in the water specimens obtained from major treatment units of the sewage treatment plant on a selected campus; (2) to treat emerging contaminants containing solutions by a combined treatment system of the simultaneous electrocoagulation/electrofiltration (EC/EF) process coupled with tubular carbonaceous/ceramic composite membrane and evaluate its feasibility of treating campus sewage; (3) to analyze the components of membrane fouling using Hermia’s model and resistances in series model. Through long term monthly monitoring (from September 2010 to June 2012), cefalexin, caffeine, and sulfamethoxazole were detected at relativly higher concentrations (up to 20,332.1 ng/L, 30,490.2 ng/L, and 2,120.8 ng/L, respectively) and frequency detected (72.7%, 100% and 100%, respectively). The results of bi-hourly monitoring on a 24 h basis showed the ranges of removal efficiencies of concerned pharmaceuticals (including 1,1-dimethylbiguanide hydrochloride, cefalexin, tetracycline, caffeine, sulfamethoxazole, erythromycin, naproxen, triclosan, ibuprofen, diclofenac, and gemfibrozil) by the following treatment units of the selected campus WWTP: (1) up-flow anaerobic sludge bed reactor: 46.03-61.12%; (2) contact aeration unit: 31.39-59.73%; (3) secondary sedimentation tank: 12.75-15.53%, and (4) disinfection unit: 6.04-23.23%. Furthermore, the experimental design using the response surface methodology (RSM) was employed to evaluate the performance of the EC/EF process in conjunction with tubular carbonaceous/ceramic composite membrane in removing emerging contaminants from aqueous solutions. The resulting optimal conditions for simultaneous optimization for the tubular carbon/alumina composite membrane (TCACM) were determined to be the electric field strength of 45.71 V/cm and transmembrane pressure of 156.45 kPa. The corresponding optimal conditions for the tubular carbon fibers/carbon/alumina composite membrane (TCCACM) were 35.53 V/cm and 330.59 kPa, respectively. Finally, the membrane fouling was analyzed using Hermia’s model and resistances in series model for the selected campus sewage. Based on Hermia’s model, it was found that the major fouling mechanism for TCACM was intermediate blocking, whereas cake formation for TCCACM. Based on resistances in series model, the results showed that TCCACM had lesser irreversible resistance component (Rirr) than that of TCACM. When using TCCACM to treat the selected campus sewage, fouling in the first 10 min was mainly irreversible, then gradually became reversible afterward. Accordingly, the carbon fiber layer on TCCACM indeed could enhance the treatment performance as compared with TCACM.