Degradation Of Amoxicillin Wastewater By Fenton-like Processes

Large quantities of antibiotics are administered to humans and animals to treat diseases and infection every year. Antibiotics are also commonly used at sub-therapeutic levels to livestock to prevent diseases and promote growth. But antibiotic resistance caused by misuse of the consequences has become a public health problem affecting public health. Environmental pollution caused by antibiotics abuse is very serious. Antibiotics wastewater, which inhibits the growth and metabolic processes of microorganisms in wastewater, is generally characterized by complex components, toxicity and non-biodegradability.The degradation of Amoxicillin simulated wastewater by two Fenton-like processes (electro-Fenton process and Fe3+(EDTA)/H2O2 system) have been investigated. The two processes were used to improve COD removal efficiency and biodegradability of Amoxicillin wastewater, and to expand demanded pH range in the reaction. The degradation rule of Amoxicillin was also discussed.The experiment results show that electro-Fenton process, including Fenton oxidation and electrolysis, was superior to Fenton process for COD removal efficiency. This is mainly due to electrochemical regeneration of Fe2+ at cathode, which can catalyze H2O2 to continuously produce more-OH. The influence of process variables such as initial H2O2 concentration, Fe2+:H2O2 molar ratio, electric current and pH on 0.1g/L Amoxicillin degradation were evaluated. At optimum reaction condition:[H2O2] =13mmol/L, [Fe2+]:[H2O2]=1:36,1=0.3A, pH=4.5,70% COD were removed and the BOD5/COD ratio increased from 0 to 0.41 after 100min treatment. The Fe2+:H2O2 molar ratio of 1:36 can also be used to degrade high concentration Amoxicillin wastewater. The detection of Amoxicillin degradation products, based on liquid chromatography-tandem mass spectrometry (LC-MS), showed that theβ-lactam ring and the R side-chain of Amoxicillin were broken. The potential degradation way of Amoxicillin was proposed.Fe3+(EDTA)/H2O2 system was used to treat Amoxicillin wastewater in neutral condition, and the characteristics of the catalyzing and degradation of Amoxicillin were studied. In the system, the addition of EDTA improved the solubility, reactivity and catalytic efficiency of Fe3+, as a result improved COD removal efficiency, and expanded the demanded pH range in the reaction. The influence of various operational parameters on Amoxicillin degradation was investigated. In the best operational condition:pH=7, [Fe3+]:[EDTA]=2:1([Fe3+]=0.80mmol/L), [H2O2]=65mmol/L, T=20℃, after 300 min, COD removal efficiency reached to 62.5%. EDTA in the experiment was catalyzer as well as reactant, which effectively avoided the possibility of secondary environmental pollution, and contributed to the degradation of penicillin antibiotics wastewater in neutral or alkaline condition. The detection by Infrared Spectra (IR) showed that theβ-lactam ring of Amoxicillin was broken, and the degradation products contain some aliphatic compounds.