Removal of micro organic pollutants in high salinity wastewater by comproportionation system of Fe(VI)/Fe(III): Enhancement of chloride and bicarbonate

Yuanxiang Mao; Jialiang Liang; Lei Jiang; Qiushi Shen; Qian Zhang; Caocong Liu; Hao Zheng; Yong Liao; Xuekang Cao; Huiyu Dong; Fangying Ji

doi:10.1016/j.watres.2022.118182

Removal of micro organic pollutants in high salinity wastewater by comproportionation system of Fe(VI)/Fe(III): Enhancement of chloride and bicarbonate

Water Res. 2022 May 1:214:118182. doi: 10.1016/j.watres.2022.118182. Epub 2022 Feb 12.

Authors

Affiliations

¹ College of Environment and Ecology, Chongqing University, Chongqing 400045, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
² Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
³ College of Environment and Ecology, Chongqing University, Chongqing 400045, China. Electronic address: jfy@cqu.edu.cn.

PMID: 35196621
DOI: 10.1016/j.watres.2022.118182

Abstract

The high concentration of salt in industrial wastewater has a strong inhibitory effect on the removal of pollutants by free radicals. A method has been developed to effectively remove micro organic pollutants in industrial high-salinity wastewater. This study investigated the combination of ferrate(VI) (Fe^VIO₄^2-, Fe(VI)) and Fe(III) on the reduction of the pollutants in synthetic high-salinity wastewater, while focusing on the effects of major inorganic substances. Whether in synthetic wastewater with or without salinity, Fe(VI)-Fe(III) process exhibited higher pollutants removal rates than Fe(VI). Both chloride (increasing from (2.2 ± 0.1) × 10^-2 min^-1 to (1.1 ± 0.03) × 10^-1 min^-1) and bicarbonate (increasing from (2.2 ± 0.1) × 10^-2 min^-1 to (1.1 ± 0.02) × 10^-1 min^-1) significantly enhanced the removal of pollutants by the Fe(VI)-Fe(III) process. Chloride changed the ionic strength of Fe(VI), but Fe(III) strengthened the formation of Fe(V)/Fe(IV) from FeO₄^2-, which offset the effect of the decrease of HFeO₄^-. Bicarbonate complexed Fe(V)/Fe(IV), these complexes enhanced the oxidizing ability of Fe(V)/Fe(IV). Based on the Program Kintecus, Fe(IV) was proposed as the main iron species in Fe(VI)-Fe(III) system, and its concentration was 2 to 3 orders of magnitude higher than Fe(V) at pH 9.0. The enhancement of Fe(VI)-Fe(III) system was observed in the oxidation of pollutant in real wastewater. Overall, the Fe(VI)-Fe(III) process is a new option for treating organic pollutants in industrial high salinity wastewater.

Keywords: Bicarbonate; Chloride; Fe(III); Ferrate(VI); High salinity wastewater.