Removal of calcium hardness from solution by fluidized-bed homogeneous crystallization (FBHC) process

Nicolaus N.N. Mahasti, Yu Jen Shih, Xuan Tung Vu, Yao-Hui Huang

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Calcium is one of the divalent ions contributing to the hardness level of the water. This work describes the removal of calcium ions from aqueous solution using carbonate salts as precipitants and the recovery of homogeneous calcium carbonate crystals via a fluidized-bed homogeneous crystallization (FBHC) process without a heterogeneous seed material. The considered parameters were effluent pH, initial molar ratio of carbonate salt to Ca, up-flow velocity, and cross-section loading. The removal efficiency of Ca hardness reached 95% at the optimal pH of 10–11 and the corresponding crystallization ratio was 88% for initial concentrations of Ca of 50–330 ppm. The FBHC process was effective with a cross-section loading of calcium in the water of up to 4.5 kg/m2/h. The efficiency of Ca immobilization as the crystal grew on the fluidized pellets was greatly improved by adjusting the degree of supersaturation in the range 2–3, resulting in the crystallization ratio (CR) and total removal of Ca (TR) of 88% and 92%, respectively. XRD analysis revealed that the formed crystals comprised two calcium carbonate (CaCO3) phases—calcite and aragonite. SEM images of the surface morphology revealed that calcium carbonate particles (around 1–2 mm) were formed by the aggregation of fine crystals (around 5 µm).

Original languageEnglish
Pages (from-to)378-385
Number of pages8
JournalJournal of the Taiwan Institute of Chemical Engineers
Volume78
DOIs
Publication statusPublished - 2017 Sep 1

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Calcium Carbonate
Crystallization
Fluidized beds
Calcium
Calcium carbonate
Hardness
Crystals
Carbonates
Salts
Ions
Water
Supersaturation
Flow velocity
Surface morphology
Seed
Effluents
Agglomeration
Recovery
Scanning electron microscopy

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this

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title = "Removal of calcium hardness from solution by fluidized-bed homogeneous crystallization (FBHC) process",
abstract = "Calcium is one of the divalent ions contributing to the hardness level of the water. This work describes the removal of calcium ions from aqueous solution using carbonate salts as precipitants and the recovery of homogeneous calcium carbonate crystals via a fluidized-bed homogeneous crystallization (FBHC) process without a heterogeneous seed material. The considered parameters were effluent pH, initial molar ratio of carbonate salt to Ca, up-flow velocity, and cross-section loading. The removal efficiency of Ca hardness reached 95{\%} at the optimal pH of 10–11 and the corresponding crystallization ratio was 88{\%} for initial concentrations of Ca of 50–330 ppm. The FBHC process was effective with a cross-section loading of calcium in the water of up to 4.5 kg/m2/h. The efficiency of Ca immobilization as the crystal grew on the fluidized pellets was greatly improved by adjusting the degree of supersaturation in the range 2–3, resulting in the crystallization ratio (CR) and total removal of Ca (TR) of 88{\%} and 92{\%}, respectively. XRD analysis revealed that the formed crystals comprised two calcium carbonate (CaCO3) phases—calcite and aragonite. SEM images of the surface morphology revealed that calcium carbonate particles (around 1–2 mm) were formed by the aggregation of fine crystals (around 5 µm).",
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Removal of calcium hardness from solution by fluidized-bed homogeneous crystallization (FBHC) process. / Mahasti, Nicolaus N.N.; Shih, Yu Jen; Vu, Xuan Tung; Huang, Yao-Hui.

In: Journal of the Taiwan Institute of Chemical Engineers, Vol. 78, 01.09.2017, p. 378-385.

Research output: Contribution to journalArticle

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