University of Oulu

Pesonen, J., Janssens, F., Hu, T., Lassi, U., & Tuomikoski, S. (2022). Precipitation of struvite using MgSO4 solution prepared from sidestream dolomite or fly ash. Heliyon, 8(12), e12580.

Precipitation of struvite using MgSO₄ solution prepared from sidestream dolomite or fly ash

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Author: Pesonen, Janne1; Janssens, Fien2; Hu, Tao1;
Organizations: 1Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland
2Life sciences & Chemistry, Thomas More, Geel, Antwerp, 2440, Belgium
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2023-05-30


Struvite (NH₄MgPO₄∗6H₂O) is a slow-release fertilizer produced from phosphorus and nitrogen-containing wastewater in the presence of Mg salts. Commercial Mg salts are the single most significant cost of struvite precipitation. In this study, H₂SO₄ formed as an industrial sidestream was used to prepare MgSO₄ solution from waste dolomite (DOL) and fly ash (FA). MgSO₄ solution was then used to precipitate struvite from a synthetic (NH₄)₂HPO₄ solution and from actual industrial process waters. The best results were obtained with real process waters where over 99% of phosphate and about 80% ammonium removals were achieved with both MgSO4 solutions after 30 min of reaction time. A higher molar ratio between Mg and P improved the phosphate removal efficiency, especially with DOL-based MgSO4 solutions; however, it had no practical effect on ammonium removal. The struvite content of precipitates was 75.49% with an FA-based chemical and 60.93% with a DOL-based chemical; other valuable nutrients (Ca, K, S, Fe, Mn, and Cl) were captured in the precipitates. The results indicate that both sidestream-based reagents perform well in struvite precipitation and that the formed precipitates could be used as fertilizers.

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Series: Heliyon
ISSN: 2405-8440
ISSN-E: 2405-8440
ISSN-L: 2405-8440
Volume: 8
Issue: 12
Article number: e12580
DOI: 10.1016/j.heliyon.2022.e12580
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
1172 Environmental sciences
215 Chemical engineering
Funding: This work was supported by the auspices of the WaterPro project of European Regional Development Fund (A74635), and the EXPO-STV project of the Academy of Finland (346537).
Academy of Finland Grant Number: 346537
Detailed Information: 346537 (Academy of Finland Funding decision)
Copyright information: © 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (