TY - JOUR
T1 - Interaction of divalent metals with struvite
T2 - sorption, reversibility, and implications for mineral recovery from wastes
AU - Goswami, Omanjana
AU - Rouff, Ashaki A.
N1 - Publisher Copyright: © 2022 Informa UK Limited, trading as Taylor & Francis Group.
PY - 2022
Y1 - 2022
N2 - Phosphorus (P) recovered from wastewater as struvite (MgNH4PO4·6H2O) can meet high P demands in the agricultural sector by reuse as a P fertiliser. Heavy metals are prevalent in wastewaters and are common fertiliser contaminants, therefore struvite as a sorbent for metals requires evaluation. Struvite sorption experiments were conducted in model solutions with cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) at 1–5 μM concentrations from pH 7–10. The struvite metal loading increased with dissolved metal concentration and pH, ranging from 2 to 493 mg kg−1. Highest loadings were observed for 5 μM Pb, which exceeded the 120 mg kg−1 European Union (EU) struvite fertiliser limit at all pH values. At 5 μM concentrations, Ni and Cd loadings exceeded EU limits of 100 mg kg−1 at pH 10, and 60 mg kg−1 at pH 8–10, respectively. In desorption experiments, 10–85% metal was released after resuspension in metal-free solutions, with a positive correlation between initial loading and amount desorbed. Distortions of the struvite phosphate band, by Fourier transformation infrared (FTIR) spectroscopy, indicated lowered symmetry of phosphate vibrations with metal sorption. X-ray absorption fine structure spectroscopy (XAFS) analysis of pH 9 solids indicated tetrahedral coordination for Cu and Zn, octahedral coordination for Co and Ni, and Pb in 9-fold coordination. Precipitation of Pb-phosphate minerals was a primary mechanism for Pb sorption. The results provide insight into metal contaminant sorption with struvite in wastewaters, and the potential for metal desorption after recovery.
AB - Phosphorus (P) recovered from wastewater as struvite (MgNH4PO4·6H2O) can meet high P demands in the agricultural sector by reuse as a P fertiliser. Heavy metals are prevalent in wastewaters and are common fertiliser contaminants, therefore struvite as a sorbent for metals requires evaluation. Struvite sorption experiments were conducted in model solutions with cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) at 1–5 μM concentrations from pH 7–10. The struvite metal loading increased with dissolved metal concentration and pH, ranging from 2 to 493 mg kg−1. Highest loadings were observed for 5 μM Pb, which exceeded the 120 mg kg−1 European Union (EU) struvite fertiliser limit at all pH values. At 5 μM concentrations, Ni and Cd loadings exceeded EU limits of 100 mg kg−1 at pH 10, and 60 mg kg−1 at pH 8–10, respectively. In desorption experiments, 10–85% metal was released after resuspension in metal-free solutions, with a positive correlation between initial loading and amount desorbed. Distortions of the struvite phosphate band, by Fourier transformation infrared (FTIR) spectroscopy, indicated lowered symmetry of phosphate vibrations with metal sorption. X-ray absorption fine structure spectroscopy (XAFS) analysis of pH 9 solids indicated tetrahedral coordination for Cu and Zn, octahedral coordination for Co and Ni, and Pb in 9-fold coordination. Precipitation of Pb-phosphate minerals was a primary mechanism for Pb sorption. The results provide insight into metal contaminant sorption with struvite in wastewaters, and the potential for metal desorption after recovery.
KW - FTIR
KW - Struvite
KW - XAFS
KW - metals
KW - phosphorus
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U2 - https://doi.org/10.1080/09593330.2022.2027026
DO - https://doi.org/10.1080/09593330.2022.2027026
M3 - Article
C2 - 35019833
SN - 0959-3330
JO - Environmental Technology
JF - Environmental Technology
ER -