Tetracycline degradation and mineralization by the coupling of an electro‐Fenton pretreatment and a biological process

BACKGROUND Studies on the degradation and mineralization of tetracycline by means of the electro‐Fenton process are lacking in the available literature. Its relevance as a pre‐treatment prior to a biological process for the removal of tetracycline was therefore examined.RESULTS Degradation followed pseudo‐first‐order kinetics and the optimal operating conditions were: 0.1 mmol L ‐1 catalyst (Fe 2+ ) concentration, 300  mA applied current intensity and 25 mg L ‐1 tetracycline, leading to total degradation within only 5 min and a mineralization yield of 89 % after 6 h electrolysis. Biodegradability tests were realized with 100 mg L ‐1 tetracycline; BOD 5 / COD ratio increased from 0.02 to 0.56 after 6 h electrolysis, showing the relevance of the electro‐Fenton pre‐treatment. However, to keep a significant residual organic content, 2 to 4 h electrolysis time may be more relevant, leading to BOD 5 / COD ratio and mineralization yields of 0.33–0.44 and 46–72%, respectively.CONCLUSION Activated sludge cultures of pretreated and non‐pretreated tetracycline solutions were carried out for 3 weeks. The overall TOC removal increased from 28% for the non‐pretreated tetracycline to 68 and 86% after 2 and 4 h electrolysis, confirming the efficiency of the proposed combined process. © 2012 Society of Chemical Industry