A novel advanced reduction process for the reduction of Cr(VI): Assistance of microbial metabolites

Advanced reduction processes (ARPs) have become hotspot because of their fast and efficient features in pollutant treatment. In this study, a novel ARP was raised through the assistance of biological wastewater degradation solutions (PDs), to completely reduce Cr(VI). Enterobacter cloacae YN-4, which could completely degrade 1500 mg/L phenol within 72 h, was isolated and identified. While, the content of organic acids and their derivatives in PDs was extremely high (74.76 %). After the combination of PDs with Fe(III) and UV, 10 mg/L Cr(VI) was completely reduced within 66 min, whose reduction rate of Cr(VI) was stable at various concentrations (10-100 mg/L), which was applicable on electroplating wastewater. In addition, Cr(VI) could be reduced stably (71.63 %) after 10 cycles. Compared with the reported ARPs, herein, the components was complex, which was firstly proposed that simultaneous action of polycarboxylic acids, monocarboxylic acids, amino acids and alcohols could promote and ensure the stable reduction of Cr(VI). Among them, the multispecies radicals·CO₂^- and·O^2- generated in PDs were combined with Fe(II), to co-reduce Cr(VI). This strategy produces a wide variety of radicals, which can provide an alternative pathway for remediation of various heavy metals and organic pollutants.