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Improving remineralization and manganese-removal of soft waters using a mixed CaCO₃/MgO contactor

Lena Szymoniak, Dominique Claveau-Mallet, Maryam Haddad and Benoit Barbeau

Article (2022)

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The aim of this study was to investigate the role of MgO on the long-term operation of a mixed media contactor. Specifically, the simultaneous removal of aqueous manganese and the remineralization of soft waters using pure calcite are limited by a remineralization breakthrough after 600 h of operation in the presence of high Mn concentrations (5 mg Mn/L). The introduction of as little as 5 % (m/m) MgO was able to improve the Mn removal kinetic, while maintaining remineralization objectives over 720 h of operation. After treating elevated concentrations of Mn, both media exhibited a Mn-coated layer which contributed to limiting the mass transfer from the media core to the liquid phase. X-ray photoelectron spectroscopy (XPS) identified this superficial layer as 10 % Mn oxides (MnOx) on MgO media compared to 1.4 % MnOx on calcite, suggesting the MgO acts as the preferred reaction surface during Mn removal. Therefore, it is postulated that in the presence of MgO, Mn removal is impacted by high pH conditions (pH = 10.5) which introduces a significant precipitation mechanism as Mn²⁺ is oxidized. For all the examined conditions, the formation of this coating improved Mn removal due to the autocatalytic nature of the adsorption/oxidation of dissolved manganese by MnOx. MgO is therefore thought to contribute to a complex sorption-coprecipitation process in the operation of a mixed media contactor.

Uncontrolled Keywords

Mn removal, Soft water demineralization, Calcite contactor, Sorption-co-precipitation, Sorption media coating

Subjects: 1400 Mining and mineral processing > 1400 Mining and mineral processing
1500 Environmental engineering > 1500 Environmental engineering
1500 Environmental engineering > 1501 Water quality, pollution
Department: Department of Civil, Geological and Mining Engineering
Funders: GRSNG/NSERC - Discovery Grant
Grant number: RGPIN 2020 06409
PolyPublie URL: https://publications.polymtl.ca/51475/
Journal Title: Journal of Water Process Engineering (vol. 49)
Publisher: Elsevier
DOI: 10.1016/j.jwpe.2022.102995
Official URL: https://doi.org/10.1016/j.jwpe.2022.102995
Date Deposited: 18 Apr 2023 14:59
Last Modified: 09 Apr 2024 16:06
Cite in APA 7: Szymoniak, L., Claveau-Mallet, D., Haddad, M., & Barbeau, B. (2022). Improving remineralization and manganese-removal of soft waters using a mixed CaCO₃/MgO contactor. Journal of Water Process Engineering, 49, 102995 (8 pages). https://doi.org/10.1016/j.jwpe.2022.102995


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