Acid leaching of vivianite separated from sewage sludge for recovering phosphorus and iron
Zhao, Yudong; Korving, Leon; Grönfors, Outi; Prot, Thomas; Suopajärvi, Terhi; Luukkonen, Tero; Liimatainen, Henrikki (2024-08-30)
Zhao, Yudong
Korving, Leon
Grönfors, Outi
Prot, Thomas
Suopajärvi, Terhi
Luukkonen, Tero
Liimatainen, Henrikki
Elsevier
30.08.2024
Zhao, Y., Korving, L., Grönfors, O., Prot, T., Suopajärvi, T., Luukkonen, T., & Liimatainen, H. (2024). Acid leaching of vivianite separated from sewage sludge for recovering phosphorus and iron. Water Research, 266, 122361. https://doi.org/10.1016/j.watres.2024.122361.
https://creativecommons.org/licenses/by/4.0/
© 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
© 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202409105773
https://urn.fi/URN:NBN:fi:oulu-202409105773
Tiivistelmä
Abstract
This paper examines the acid leaching efficiencies of Fe and P from vivianite slurry (VS, Fe3(PO4)2·8H2O), which is magnetically separated from anaerobic digested sludge, and elaborates on Fe and P reuse routes. The characteristics and dissolution behavior of raw VS in hydrochloric, sulfuric, phosphoric, oxalic, and citric acids are investigated. Results reveal that the primary impurities in VS are organic matter, other phosphate compounds, and Mg present in the vivianite crystal structure. Hydrochloric and sulfuric acids could effectively extract P (90%) from VS at an optimal hydrogen-to-phosphorus (H⁺/P) ratio of 2.5, compared with sewage sludge ash (SSA) that normally needs an H⁺/P ratio greater than 3. Hence, VS can be employed as an alternative P resource following a similar recovery route used with SSA. However, in comparison to SSA, VS use can decrease acid consumption in P extraction and the requirement for the extensive purification of cationic impurities. Furthermore, oxalic acid effectively facilitates the separation of P and Fe in VS by precipitating Fe as insoluble ferrous oxalate in acidic conditions, leading to a high Fe recovery rate of 95%. The recovery and reuse of Fe through the oxalic acid route further improves the feasibility of VS as an alternate resource.
This paper examines the acid leaching efficiencies of Fe and P from vivianite slurry (VS, Fe3(PO4)2·8H2O), which is magnetically separated from anaerobic digested sludge, and elaborates on Fe and P reuse routes. The characteristics and dissolution behavior of raw VS in hydrochloric, sulfuric, phosphoric, oxalic, and citric acids are investigated. Results reveal that the primary impurities in VS are organic matter, other phosphate compounds, and Mg present in the vivianite crystal structure. Hydrochloric and sulfuric acids could effectively extract P (90%) from VS at an optimal hydrogen-to-phosphorus (H⁺/P) ratio of 2.5, compared with sewage sludge ash (SSA) that normally needs an H⁺/P ratio greater than 3. Hence, VS can be employed as an alternative P resource following a similar recovery route used with SSA. However, in comparison to SSA, VS use can decrease acid consumption in P extraction and the requirement for the extensive purification of cationic impurities. Furthermore, oxalic acid effectively facilitates the separation of P and Fe in VS by precipitating Fe as insoluble ferrous oxalate in acidic conditions, leading to a high Fe recovery rate of 95%. The recovery and reuse of Fe through the oxalic acid route further improves the feasibility of VS as an alternate resource.
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