Enhanced biodegradation of perchlorate in the presence of FeCl₂ and FeCl₃

BACKGROUND: Bioreduction of perchlorate (ClO₄⁻) faces challenges such as slow degradation rates and long start-up periods, greatly limiting their practical application. This study investigated the effects of Fe(II) and Fe(III) at concentrations of 0, 0.1, 0.5, and 1 mmol L⁻¹ on the bioreduction characteristics of ClO₄⁻. RESULTS: Compared to the control group, the reduction rates of ClO₄⁻ in the Fe(II)-0.1 and Fe(III)-0.1 systems increased by 7.46-fold and 7.24-fold, respectively. Complete degradation of ClO₄⁻ up to 1586.32 ± 18.60 mg L⁻¹ could be achieved within 96 h. CONCLUSION: The results demonstrate that the addition of Fe(II) and Fe(III) effectively improves issues such as long start-up periods and slow degradation rates in the bioreduction of ClO₄⁻. The presence of Fe enhances the secretion of cytochrome c on the cell membrane, and the reversible redox reaction between Fe(II) and Fe(III) enhances electron transfer during the ClO₄⁻ reduction process. Furthermore, increased total membrane permeability promotes the absorption and utilization of nutrients by cells, accelerating cellular growth and metabolism. Analysis of the microbial community structure revealed that the addition of Fe(III) favored the abundance of Patescibacteria, Bacteroidota, and Firmicutes, facilitating extracellular electron transfer during high chlorate salt reduction and significantly enhancing the bioreduction efficiency of ClO₄⁻.