Enhancement of emerging contaminants removal using Fenton reaction driven by H2O2-producing microbial fuel cells

Abstract

The discharge of emerging contaminants (ECs) into the environment has raised great concerns due to their negative effects on the ecosystem. Intensive research efforts have been undertaken in order to find effective methods to treat these compounds. In this study, the removal of four ECs including Bisphenol A (BPA), Estrone (E1), Sulfamethazine (SM2), Triclocarban (TCC) was investigated in the microbial fuel cell (MFC)-Fenton system. Glucose and graphite rod with stacked graphite granules were used as the substrate and electrode, respectively since they improved current density of MFCs system and increased cathodic H2O2 synthesis. Both batch and continuous flow modes of MFCs were compared and the operational parameters for higher H2O2 yield were also studied. The results showed that for both batch and continuous flow modes, initially the H2O2 production had a rising trend and arrived at the highest level but subsequently it decreased. We later demonstrated that controlling pH at 3 would promote H2O2 accumulation. Integrating the in-situ H2O2 synthesis and Fe2+ addition in the cathodic chamber, production of hydroxyl radicals was evidenced through salicylic acid degradation and formation of its hydroxyl products. The MFC-Fenton system could effectively remove E1, BPA, TCC and SM2. Our results showed that the removal of ECs was attributed to the oxidation by OH and the adsorption on graphite materials. The contribution of the two removal mechanisms to the overall removal will vary with different ECs depending on the ECs reactivity in Fenton reaction. This study demonstrates the application of the MFC-Fenton technology to effectively remove E1, BPA, TCC and SM2, which provides a promising and cost-effective alternative for future ECs removal.