Oxidants-assisted sand filter to enhance the simultaneous removals of manganese, iron and ammonia from groundwater: Formation of active MnOx and involved mechanisms

Haiyang Yang; Xiaobin Tang; Xinsheng Luo; Guibai Li; Heng Liang; Shane Snyder

doi:10.1016/j.jhazmat.2021.125707

Oxidants-assisted sand filter to enhance the simultaneous removals of manganese, iron and ammonia from groundwater: Formation of active MnOx and involved mechanisms

J Hazard Mater. 2021 Aug 5:415:125707. doi: 10.1016/j.jhazmat.2021.125707. Epub 2021 Mar 22.

Authors

Haiyang Yang¹, Xiaobin Tang², Xinsheng Luo², Guibai Li², Heng Liang³, Shane Snyder⁴

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, 637141, Singapore.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
³ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China. Electronic address: hitliangheng@163.com.
⁴ Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, 637141, Singapore. Electronic address: ssnyder@ntu.edu.sg.

PMID: 34088191
DOI: 10.1016/j.jhazmat.2021.125707

Abstract

Oxidants are routinely employed to remove manganese from groundwater deeply, but the conversion pathway of manganese in the process still needed to be explored. In this study, potassium permanganate and sodium hypochlorite were introduced to explore their start-up effect on sand filters in treating high concentration of manganese (1.42-1.94 mg/L). The addition of potassium permanganate would effectively enhance the manganese removal (>97%) and significantly shorten the start-up period (36 days) compared to sodium hypochlorite-added filter (90 days). A good correlation between manganese deposition concentration and manganese removal rate was obtained, which indicated that the removal of manganese in pre-adding oxidants sand filters was dominated by adsorption and auto-catalytic oxidation processes, where δ-MnO₂ played a crucial role and the contribution of bacteria was negligible. The addition of potassium permanganate facilitated the production of MnO₂ and promoted the conversion of Mn(II)-γ-MnO₂-δ-MnO₂/todorokite during the 120-day operation. Besides, the residual Mn(II) contributed to converting the freshly generated MnO₂ by pre-adding oxidants into active MnOx. XPS results demonstrated the co-existence system of Mn(II), Mn(III) and Mn(IV) in δ-MnO₂. The proportion of Mn(III) with high catalytic oxidative activity in potassium permanganate-assisted formed MnOx (57%) was much higher than in sodium hypochlorite-assisted formed MnOx (22%). These findings have practical significance to develop new strategies for rapid, safe and deep removal of manganese.

Keywords: Active manganese oxides; Auto-catalytic oxidation; Groundwater; Manganese removal; Pre-oxidation.

Publication types

Research Support, Non-U.S. Gov't