Degradation of Tetracycline by Advanced Oxidation Processes : Sono-Fenton and Ozonation Process

• Main Authors: HUANG,BO-MING, 黃柏銘
• Other Authors: WANG,CHI-KANG
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/j3q2h9

碩士 === 元培醫事科技大學 === 環境工程衛生系碩士班 === 104 === Among a wide variety of pharmaceuticals and personal care products (PPCPs), tetracycline antibiotics are one of the largest groups of pharmaceutical compounds extensively used in human and veterinary medicine to treat and prevent bacterial infections. As these PPCPs presented in the industrial wastewater, even the concentrations of PPCPs in solution phase are very low, the bio-refractory and un-biodegradable characteristics lead the risk and harmful effect to the water and soil environments. Hence, in this study, two advanced oxidation processes such as ozonation and sono-Fenton processes were conducted individually to degrade the tetracycline for investigating their feasibility on tetracycline degradation. Effect of operational variables such as pH, temperatures, ultrasonic power, types and flow rates of aeration, addition of anions and flow rate of ozone gas on tetracycline degradation and change of toxicity were also proposed. In addition, the comparisons of tetracycline by seven processes based on the combination of ultrasound (US), Fenton and ozonation were investigated. Experimental results indicated that the contribution of Fe2+ and H2O2 in ultrasonic system on the degradation of tetracycline was significant, where the maximum tetracycline degradation efficiency in sono-Fenton process was as high as 90% followed by 90% mineralization at pH 3, 55oC, 100 Watts, aeration of air with 0.2 L/min for 60 minutes. Effect of initial pH level on tetracycline degradation was insignificant from pH 3 to pH 6 but significantly decreased as the pH was greater than pH 7. Increase of the ultrasonic power was slightly increased the degradation efficiency of tetracycline, which indicated that the hydroxyl radicals dominated the oxidation of tetracycline. Effects of aeration of air or oxygen with different flows and reaction temperatures were insignificant. Addition of anions in the solution inhibited the degradation and mineralization of tetracycline from 90% to 31.5% and 30% to 7.7%, respectively. Ozonation showed better efficiencies in tetracycline degradation, where the optimum reaction condition was found at pH 3, 0.2 L O3/min and 25oC with almost 100% tetracycline degradation and 34% mineralization. The comparisons of seven processes such as sole ultrasound, Fenton, sono-Fenton, O3, US/O3, Fenton/O3 and US/Fenton/O3 showed that the US/Fenton/O3 process led to 99.8% degradation and 64% mineralization of tetracycline, which revealed that the combination of US/Fenton/O3 synergistically increased the mineralization of refractory compounds. The toxicity of tetracycline was significantly decreased due to the mineralization of tetracycline, where the cell viability increased to 89% and 70% from less than 50% (original tetracycline). Therefore, the results shown in this study proposed that the AOPs can directly degrade and mineralize the tetracycline and reduce the formation of intermediates and toxicity.