Anaerobic cyanides oxidation with bimetallic modulation of biological toxicity and activity for nitrite reduction

Acong Chen; Haoling Li; Haizhen Wu; Zhaohui Song; Yao Chen; Heng Zhang; Zijun Pang; Zhi Qin; Yulun Wu; Xianghong Guan; Hua Huang; Zemin Li; Guanglei Qiu; Chaohai Wei

doi:10.1016/j.jhazmat.2024.134540

Anaerobic cyanides oxidation with bimetallic modulation of biological toxicity and activity for nitrite reduction

J Hazard Mater. 2024 May 7:472:134540. doi: 10.1016/j.jhazmat.2024.134540. Online ahead of print.

Authors

Acong Chen¹, Haoling Li², Haizhen Wu³, Zhaohui Song¹, Yao Chen¹, Heng Zhang¹, Zijun Pang¹, Zhi Qin¹, Yulun Wu¹, Xianghong Guan¹, Hua Huang¹, Zemin Li⁴, Guanglei Qiu¹, Chaohai Wei⁵

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China.
² School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong 510006, PR China.
³ School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong 510006, PR China. Electronic address: hzhwu2@scut.edu.cn.
⁴ School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; School of Environment, South China Normal University, Guangzhou, Guangdong 510006, PR China.
⁵ School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong 510006, PR China; School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, PR China. Electronic address: cechwei@scut.edu.cn.

PMID: 38733787
DOI: 10.1016/j.jhazmat.2024.134540

Abstract

Cyanide is a typical toxic reducing agent prevailing in wastewater with a well-defined chemical mechanism, whereas its exploitation as an electron donor by microorganisms is currently understudied. Given that conventional denitrification requires additional electron donors, the cyanide and nitrogen can be eliminated simultaneously if the reducing HCN/CN^- and its complexes are used as inorganic electron donors. Hence, this paper proposes anaerobic cyanides oxidation for nitrite reduction, whereby the biological toxicity and activity of cyanides are modulated by bimetallics. Performance tests illustrated that low toxicity equivalents of iron-copper composite cyanides provided higher denitrification loads with the release of cyanide ions and electrons from the complex structure by the bimetal. Both isotopic labeling and Density Functional Theory (DFT) demonstrated that CN^--N supplied electrons for nitrite reduction. The superposition of chemical processes reduces the biotoxicity and enhances the biological activity of cyanides in the CN^-/Fe³⁺/Cu²⁺/NO₂^- coexistence system, including complex detoxification of CN^- by Fe³⁺, CN^- release by Cu²⁺ from [Fe(CN)₆]^3-, and NO release by nitrite substitution of -CN groups. Cyanide is the smallest structural unit of C/N-containing compounds and serves as a probe to extend the electron-donating principle of anaerobic cyanides oxidation to more electron-donor microbial utilization.

Keywords: Anaerobic cyanides oxidation; Autotrophic denitrification; Bimetallic cyanides conjugates; Detoxification and cyanides releases; Nitrite reduction.