Cathode-anode coupling enhances antibiotics removal in flow-through electrochemical system

Increasing flow rate in a flow-through electrochemical systems usually improves treatment throughput but sacrifices pollutant removal efficiency because of the shortened residence time. Herein, we report a cathode-anode coupled flow-through electrochemical system that overcomes this trade-off by optimizing the sequential connection between anodic pre-oxidation, cathodic H 2 O 2 generation and reactive oxygen species conversion. A rice-husk-derived porous biomass carbon cathode supported on 304 stainless-steel felt (P-PBC/304SSL) was coupled with a 304SSL anode, and the effects of cathode and anode material, flow direction, electrode substrate were systematically regulated. The optimized anode-to-cathode flow configuration enabled efficient single-pass tetracycline degradation. In mariculture wastewater, the system maintained a tetracycline removal efficiency of 95.25%, corresponding to a large apparent rate constant of 100.45 min −1 and an area-normalized tetracycline treatment capacity of 2.86 g m −2 h −1 . Compared with the static system, the flow-through system markedly shortened the treatment time, and increased the treatment capacity by approximately 3.4 times. The involvement of ·OH, ·O 2 − and 1 O 2 indicated that cathodic H 2 O 2 generation, reactive oxygen species conversion, SSL anodic oxidation and flow-enhanced mass transfer jointly contributed to this efficient interaction. The system also showed stable operation over 200 h and a low electrical energy consumption of 0.104 kWh m −3 , highlighting the potential in continuous wastewater treatment.