Bio-electro-Fenton system for enhanced estrogens degradation

•A bio-electro-Fenton system was set up.•Estrogens were removed in the system due to adsorption and oxidation.•Two probable degradation pathways were proposed for E2.•The system was cost-effective for recalcitrant contaminants treatment. The feasibility of removing estrogens including 17β-estradiol (E2) and 17α-ethynyl-estradiol (EE2) was studied in a bio-electro-Fenton (BEF) system equipped with a Fe@Fe2O3/non-catalyzed carbon felt (NCF) composite cathode. E2 and EE2 were removed by reactive oxidants, produced by bio-electro-Fenton system and zero-valent iron/O2 system, as well as adsorption. Under closed-circuit condition, 81% of E2 and 56% of EE2 were removed within 10h in the system, in which the highest concentration of total iron ions and H2O2 reached 81 and 1.2mg/L, respectively. The maximum power density of BEF system equipped with Fe@Fe2O3/NCF electrode was 4.35W/m3. Two intermediates of E1 and 6-OH-E2 were identified during Fenton oxidation of E2. This study demonstrates the degradation fate of E2 and EE2 in a BEF system equipped with Fe@Fe2O3/NCF electrodes, which provides a promising and cost-effective solution for the removal of recalcitrant contaminants with simultaneous power generation.