Sequential adsorption-oxidation pulses for alternating electrochemical advanced pretreatment of wastewater containing tetracyclines

The pretreatment of tetracycline production wastewater (TPW) is of great environmental significance in improving its biodegradability and reducing the risk of resistance genes. A novel sequential adsorption-oxidation pulses (SAOP) electrochemical method was proposed, and 95.6 % of tetracycline hydrochloride (TCH) was removed in 60 min with the enhancement of BOD₅/COD_Cr from 0.18 to 0.44. The results of in-situ electrochemical electron magnetic resonance and electro-adsorption experiments indicate that the mild negative pulse makes the targeting TCH electromigration and adsorb on an electrode surface, and then the positive pulse forces TCH to be oxidized. Presumable mechanisms for enhancing TCH removal was proposed as (1) ameliorative mass transfer, (2) the pre-adsorbed TCH modifies the electrode surface to facilitate subsequent oxidation or ROS generation. The pretreatment of SAOP reduces the toxicity of TPW on activated sludge and decreases its inhibition of cell activity. Finally, considering the intended use, the performance of SAOP was validated in actual TPW. The pretreatment results are achieved in terms of removal and biodegradability, as well as reduction of resistance genes’ accumulation in the biochemical unit. This research provides a novel method for solving the contradiction between mass and charge transfer in the electrochemical oxidation of positively charged pollutants and a reproducible readily method for the electrochemical pretreatment of recalcitrant antibiotic production wastewater. Copyright © 2025 Elsevier B.V.