Column experiments study on attenuation of perchlorate stimulated by sulfur

Abstract

Perchlorate (\begin{document}${\mathrm{ClO}}_4^- $\end{document}) is a new persistent pollutant with small molecular weight, rapid diffusion, and high stability. It is widely found in the environment, especially in the areas where fireworks are produced and set off intensively. Perchlorate impacts the normal function of thyroid gland; its environmental pollution attracted wide attention and has become a research hotspot in the field of environmental science in recent years. Column experiments using river sand from polluted site as the experiment material were conducted to study on the mechanism and influencing factors of the attenuation of perchlorate stimulated by sulfur. The effects of groundwater, iron oxides, and nitrate (\begin{document}${\mathrm{NO}}_3^- $\end{document}) were investigated in this study. The results show that sulfur is able to stimulate \begin{document}${\mathrm{ClO}}_4^- $\end{document} attenuation, which mainly depends on microbial degradation, and it is limited by the lack of essential inorganic salts and other nutrients for microorganisms. Iron oxides have a buffering effect on the decrease of pH, but have a limited stimulating effect on the \begin{document}${\mathrm{ClO}}_4^- $\end{document} attenuation in the column. Groundwater significantly enhanced sulfur-stimulated \begin{document}${\mathrm{ClO}}_4^- $\end{document} attenuation and microbial acid production. The degradation of nitrate (\begin{document}${\mathrm{NO}}_3^- $\end{document}) in groundwater is preferred to that of \begin{document}${\mathrm{ClO}}_4^- $\end{document}; when \begin{document}${\mathrm{NO}}_3^- $\end{document} concentration is less than about 10 mg/L, \begin{document}${\mathrm{ClO}}_4^- $\end{document} begins to be reducted significantly. Sulfur has the potential as the PRB reaction medium for in-situ remediation of pollutants such as \begin{document}${\mathrm{ClO}}_4^- $\end{document} and \begin{document}${\mathrm{NO}}_3^- $\end{document}. This study provides a theoretical basis and data support for the practical application of environmental remediation.

Keywords

• perchlorate
• sulfur
• stimulated attenuation
• microbial degradation
• groundwater
• iron oxides
• nitrate