Hybrid bio-activated sludge-electro-Fenton system for a sustainable removal of cefuroxime sodium antibiotic in aqueous medium: optimization, biodegradability improvement and mechanism

Nanotechnologies promise to bring about a major revolution in a number of areas, from health to environmental protection, health and environmental protection. This is the promise of the application of graphite electrodes modified by gold nanoparticles in the Electro-Fenton process. In this study, a strategy combining homogeneous Electro-Fenton pretreatment with biologically activated sludge treatment "AS-EF" was implemented to effectively destroy the antibiotic Cefuroxime Sodium (CFX-Na) in aqueous media. First, the performance of a homogeneous Electro-Fenton process for degrading and mineralizing Cefuroxime Sodium (CFX-Na) in aqueous media was evaluated and optimized. In fact, CFX-Na (0.15 mM) was completely decomposed after 15 min of electrolysis at 400 mA current and almost completely mineralized (99% COD removal) after 6 h, indicating the efficiency of the "Electro-Fenton" process. The aromatic by-products were identified using LC–MS/MS, and a potential degradation mechanism was suggested. The process was then optimized by response surface methodology (RSM), considering the Central Composite Design (CCD), to analyze the interactive effects of process variables on the COD removal rate. In addition, biodegradability tests of the solutions before and after electrolysis showed that an increase in the BOD 5 /COD ratio from 0.0068 to 0.405 was obtained after 2 h of oxidation by EF, confirming the biodegradability of the electrolyzed solution. Then, a biological treatment using activated sludge was successfully performed to complete the mineralization of biodegradable organic compounds. In fact, the bio-process succeeded in mineralizing 99% of the entire CFX-Na solution after about 20 days, proving the applicability of the suggested method and its potential to handle wastewater including antibiotic medication residues.