Treatment of 2,4,6-tribromophenol-contaminated water using iron ion/calcium sulfite: the dual role of oxidation and coagulation†

2,4,6-Tribromophenol (TBP) is widely distributed in environmental media, posing potential risks to human health and ecological system. The efficient treatment of TBP-contaminated water is a significant challenge. In this study, a combined process of oxidation and coagulation using Fe(III)/CaSO₃ was employed to treat actual water samples spiked with TBP. The slow release of S(IV) from CaSO₃ into the solution benefited the treatment efficiency, and the Fe(III)/CaSO₃ system not only effectively removed TBP but also significantly enhanced the removal of background organic compounds via oxidation and coagulation. The optimal water quality was achieved with Fe(III) and CaSO₃ dosages of 100 μM and 400 μM, respectively, with an initial pH of 3.5. As for the Fe(III)/CaSO₃ system, larger-sized crystals were observed after treating the secondary clarifier effluent compared to that in the sole Fe(III) coagulation process. Further coagulation after Fe(III)/CaSO₃ oxidation offers a new approach to apply S(IV)-based advanced oxidation technologies in the field of water treatment, demonstrating its potential in the effective treatment of TBP in water.