Study On Advance Treatment Of Oxytetracycline Wastewater By Microwave-Fenton Oxidation

In this research subject, Advanced treatment experiments for secondary effluent of oxytetracycline wastewater were studied by Fenton oxidation and Microwave-Fenton oxidation, respectively. The optimal treatment process and reaction conditions were determined through the contrast analysis, and then the reactive appare dynamic behavior was studied, the degradation mechanism and methods of oxytetracycline were also discussed.so it will offer some effective technologies for oxytetracycline wastewater treatment, and the main conclusions were as following:1) The results of advanced treatment experiments by Fenton oxidation and Microwave-Fenton oxidation indicated that:The final effluent of both methods would meet the standards, but by Microwave-Fenton oxidation, the dosage of H2O2and Fe2+reduced by20%, the reaction time was shortened by90%and removal rate was2%higher. The best operating conditions of which were pH=3.0, H2O2=4mL/L, H2O2/Fe2+molar ratio=25, the microwave power=625W. Under the most favorable conditions, the COD of final effluent was reduced from502-516mg/L to lower than120mg/L, and the removals of more than78%were observed for COD at reaction time6min. In final effluent, there was no oxytetracycline residue, the index of COD, NH3-N, acute toxicity and BOD5met the requirements of the second chart in discharge standards of "Water Pollutants for Pharmaceutical Industry Fermentation Products Category"(GB21903-2008).2) The apparent kinetics study on Oxytetracycline degradation showed that:the apparent kinetics equation of oxytetracycline by Fenton oxidation was V=1.0866×10-2AOTC1.0840BH2o20.4396CFe2+0.2627, and the degradation reaction order was1.7863; the apparent kinetics equation by Microwave-Fenton oxidation was V=2.3023×10-1AOTC0.8547BH2o20.3376CFe2+0.8799,and the degradation reaction order was2.0722, and. Combined with the results of wastewater treatment, the Microwave had synergistic effect on Fenton oxidation, which indicted contribution to accelerate the rate of reaction of oxytetracycline and reduce the reaction time.3) The intermediate products by Microwave-Fenton oxidation were determined through UV-Vis, HPLC, HPLC/MS/MS method. Two main intermediate products A and B were obtained, the molecular weight of which were226and158respectively. The pathways of oxytetracycline degradation was proposed:The2-Acylamino and4-dimethylamino were damaged in ring A, the hydroxylation was obtained in ring D, In ring C,6-hydroxy had a ring-opening reaction, the product A was obtained in this way, then3-hydroxy in ring A caused to the dehydration reaction with5,12-hydroxy in ring B of product A.