Coagulation efficiency, floc properties and membrane fouling of polyaluminum chloride in coagulation-ultrafiltration system: THE role of magnesium

Shuang Zhao, Baoyu Gao, Shenglei Sun, Qinyan Yue, Hongyu Dong, Wen Song

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The influence of magnesium on coagulation-ultrafiltration process was investigated regarding coagulation efficiency, floc properties and the subsequent impact on membrane fouling. PACl with different basicity values (B, OH/Al3+molar ratio) were used as coagulants. Fulvic acid (FA) water and high hardness FA water (containing magnesium) were used as original water in this study. Floc characteristics were investigated using a laser diffraction particle sizing device while membrane fouling was evaluated by a dead-end ultrafiltration batch unit. The results showed that PACl with higher OH/Al3+ value was more efficient for FA removal. Moreover, the addition of magnesium could improve its coagulation efficiency. Flocs generated in FA-magnesium water was smaller than that of FA water and showed a lower Df value, which indicated that these flocs had open structures. Results of ultrafiltration test showed that membrane fouling became severe as OH/Al3+ value increasing in FA water, but could be reduced apparently when magnesium was added. In addition, the permeate pH increased as OH/Al3+ values growing whereas the permeate pH of FA-magnesium solution was higher than that of FA solution regardless of the original pH and coagulants.

Original languageEnglish
Pages (from-to)235-241
Number of pages7
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume469
DOIs
StatePublished - 1 Mar 2015
Externally publishedYes

Keywords

  • Coagulation-ultrafiltration
  • Floc characteristics
  • Magnesium
  • Membrane fouling
  • OH/Al values

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