Pretreatment of Penicillin G Wastewater by Electro-Fenton Process

Abstract: The sources of antibiotics in natural water systems may be manufacturing operations in pharmaceutical industry, therapeutic use for human and animals and high amount use as growth promoters in intensive farming. These pollution sources are emissions from production sites, hospitals, breeding farms and households. Antibiotic wastewater normally contains many organic matters including bacteriostatic and toxic as well as recalcitrant compounds and with dark color, which therefore was regarded as a non-biodegradable wastewater. They survived on the effluent of sewage treatment plant (STP) and pollute the natural water. Moreover, the residuals can get into the food chain by fish breeding and poultry raising, and then enter the human body by the food chain transport which would cause an enhanced antibody and damage human healthy.For removing the residual antibiotic in STP, separation and pretreatment of antibiotic wastewater by advanced oxidation processes (AOPs) was proposed and researched. But the application show that many AOPs were limited applied for their disadvantages such as high cost and complex process. Electro-Fenton process is one kind of AOPs, which can destroy the antibiotic molecular structure and remove their recalcitrant character as a pretreatment process. In this study, both H2O2 and Fe2+ are externally employed whereas Fe2+ is being continuously regenerated at cathode which can catalyze H2O2 to continue produce HO?. This method include oxidation and electrolysis, thus degrade the organic matter effectively. It would be a promising method for its advantages of low cost and easy operation.The degradation of penicillin G sodium (PGN) simulated wastewater by electro- Fenton has been investigated. Trials were performed in a batch reactor, aiming at both analyzing the effects of the operating conditions(pH、initial Fe2+ concentration、initial H2O2 concentration、initial PGN concentration、initial electrolyte concentration、temperature、current) on COD removal and selecting the best operating conditions of COD removal and BOD5/COD enhancement. Operating at T=20℃, pH=3, [FeSO4·7H2O]= 0.5g/L, [H2O2]=0.2mL/L, [PGN]=100mg/L, and electric current=0.3A, about 64.35% of COD was removed and an increase of the BOD5/COD ratio from 0 to 0.38 was achieved after 20 min. The detection of PGN degradation products were based on infrared spectrogram (IR) and liquid chromatography–tandem mass spectrometry (LC-MS), the result showed that theβ-lactam cyclic of PGN was broken and PGN could be degraded by biological treatment after oxidation on electro-Fenton as it lost the antiseptic ability. To be a further research, a kinetics model of the PGN degradation was establish base on the experimental data of the effects of initial Fe2+ concentration, initial H2O2 concentration, initial PGN concentration and temperature by PGN removal. The reaction rate constant and reaction order of the overall equation for PGN degradation indicate that the reaction rate is very fast and the effect of initial H2O2 concentration is greater than initial Fe2+ concentration on PGN degradation by electro-Fenton…
Key words: Electro-Fenton; Pretreatment; Penicillin G; Degradation Rule; Biodegradability; Kinetics

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