Two-stage sulfate removal from reject brine in inland desalination with zero-liquid discharge

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

This research proposes a two-stage process for the removal of sulfate from a nano-filtration (NF) reject stream. In Stage 1, calcium chloride is used to partially remove the majority of sulfate as calcium sulfate precipitate while the remaining sulfate is removed in Stage 2 as calcium sulfoaluminate precipitate. Kinetics of the removal process in both stages was investigated and the results indicated that the removal kinetics is not a limiting factor for the practicability of the process. Equilibrium characteristics of sulfate precipitation were evaluated and optimum conditions for maximum sulfate removal were obtained. Sulfate removal in Stage 1 was independent of the pH while efficient sulfate removal in Stage 2 was found to be above pH. 11. Efficient sulfate removal was observed at practical ranges of lime and sodium aluminate doses. An equilibrium model was developed to describe the chemical behavior in Stage 2. A valid explanation for the mechanism of sulfate removal in Stage 2 was the formation of a solid mixture consisting of ettringite and monosulfate as confirmed by X-ray diffraction (XRD) analysis. This approach is expected to reduce the volumes of the overall precipitated solids and in turn improve the overall efficiency of the ZLD treatment system.

Original languageEnglish
Pages (from-to)52-58
Number of pages7
JournalDesalination
Volume362
DOIs
Publication statusPublished - 5 Apr 2015

Fingerprint

Desalination
Discharge (fluid mechanics)
desalination
Sulfates
brine
sulfate
liquid
Liquids
calcium
Precipitates
Calcium
removal
Calcium Sulfate
Nanofiltration
Calcium Chloride
Kinetics
kinetics
Calcium chloride
X ray diffraction analysis
Lime

Keywords

  • Ettringite
  • Nanofiltration
  • Reject brine
  • Sulfate
  • Ultra high lime with aluminum
  • Zero liquid discharge

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Chemistry(all)
  • Materials Science(all)
  • Water Science and Technology

Cite this

Two-stage sulfate removal from reject brine in inland desalination with zero-liquid discharge. / Almasri, Dema; Mahmoud, Khaled; Abdel-Wahab, Ahmed.

In: Desalination, Vol. 362, 05.04.2015, p. 52-58.

Research output: Contribution to journalArticle

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