Colloidal silica removal in coagulation processes for wastewater reuse in a high-tech industrial park

S. H. Chuang, T. C. Chang, C. F. Ouyang, J. M. Leu

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

31 Scopus citations


Four experiments of coagulation and flocculation were conducted to investigate the characteristics of colloidal silica removal in a high-tech industrial wastewater treatment plant for reclamation and reuse of the effluent. Experimental results illustrated that poly-aluminium chloride (PACI) showed higher performances on colloidal silica removal than alum. Interestingly, the two coagulants demonstrated the same capacity on silica removal. The specific silica removal capacity was approximately 0.135 mg SiO2/mg Al2O3 when the dosage of coagulants was in the range 30-150 mg/L Al2O3. In addition, the silica was reduced significantly at the condition of pH above 8. Experimental data implied that precipitation of aluminium flocs was the major mechanism for colloid silica removal in PACI and alum coagulation, besides, charge adsorption was also important for improving removal efficiency. Moreover, the addition of polyacrylic acid (PAA) as a flocculant could slightly advance silica removal in the PACI coagulation. The combined PACI/PAA/flocs coagulation was effective for the removal of colloidal silica, soluble COD, and turbidity and also suitable as a pretreatment unit in wastewater reclamation and reuse processes.

Original languageEnglish
Title of host publicationWastewater Reclamation and Reuse for Sustainability
EditorsI.S. Kim, S. Kim, J. Cho
Number of pages9
StatePublished - 2007

Publication series

NameWater Science and Technology
ISSN (Print)0273-1223


  • Alum
  • Coagulation
  • Colloidal silica
  • Poly-aluminium chloride
  • Wastewater reuse


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