Application of Polysilicato-Iron Coagulant to Coagulation of Algae and Municipal Wastewater

  • Y. Watanabe
  • K. Hashimoto
  • T. Hasegawa
  • S. Kameda
  • H. Suzuki


A new inorganic polymer coagulant, polysilicato-iron (PSI), was developed. PSI has a molar ratio of Fe to Si of 1:1 to 1:5 and a molecular weight of 200 000 to 500 000 Da. The optimum pH ranges for the coagulation of suspended particles and soluble organics are 6.0 to 8.0 and 4.5 to 7.0, respectively. This paper deals with the effectiveness of PSI for the coagulation of municipal wastewater and algae such as Microcystis sp. and Stephanodiscus sp. Jar test results showed that, compared to aluminum sulfate (AS) and polyaluminum chloride (PAC), PSI is very effective for coagulating algae. With dosages equivalent to 0.16mmol/l Fe in PSI, the removal efficiencies of Microcystis sp. and Stephanodiscus sp. were 98 % and 99 %, respectively. This is significantly better than 20 % and 60 %, respectively, for the two species using 0.16mmol/l Al in PAC. The jet mixed separator (JMS) was used as a process unit for simultaneous flocculation and sedimentation. With a PSI dosage of 5 mgFe/l and a pH of 6.5, and a hydraulic detention time of 90 min in the JMS, the average JMS effluent turbidity and total phosphorus concentration were 27 Turbidity Unit (TU) and 0.6mg/l, respectively.


Municipal Wastewater Porous Plate Aluminum Sulfate Aluminum Sulfate Turbidity Removal 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Delejs, P.: Influence of Algae and Their Exudates on Removal of Humic Substances and Optimum Dosage of Coagulant. Wat. Sci. Techn. 27(27) (1993) 123–132.Google Scholar
  2. [2]
    Hasegawa, T. et al.: Characteristics of Metal-Polysilicate Coagulants. Wat. Sci. Tech. 23, Kyoto 1991, pp. 1713–1722.Google Scholar
  3. [3]
    Hasegawa, T. et al.: Now Polysilicic Acid Coagulants and Their Properties. Proc. of Water Nagoya’ 89, 1989, pp. 152-161.Google Scholar
  4. [4]
    Hashimoto, K. et al.: Inorganic Polymer Coagulants of Metal-Polysilicate Complex. Water Supply, Vol.9, Jongkoping 1991, pp.567–570.Google Scholar
  5. [5]
    Hashimoto, K. et al.: The Physicochemical Properties of Coagulation by Polysilicato-Aluminum Coagulant. Proc. of ICEWW’ 94, Beijing, pp. 96-103.Google Scholar
  6. [6]
    Ødegaard, H.: Coagulation as the First Step in Wastewater Treatment. In: Pretreatment in Chemical Water and Wastewater Treatment, H.H. Hahn and R. Klute (Eds.). Springer, Berlin Heidelberg New York 1988, pp. 248–260.Google Scholar
  7. [7]
    Watanabe, Y. et al.: Removal of Soluble and Particulate Organic Material in Municipal Wastewater by Chemical Flocculation and Biofilm Processes. Wat. Sci. Techn. 27(10) (1993) 123–128.Google Scholar
  8. [8]
    Watanabe, Y., Iwasaki, Y.: Performance of Hybrid Small Wastewater Treatment System Consisting of Jet Mixed Separator and Rotating Biological Contactors. Wat. Sci. Tech. 35(6) (1997) 63–70.CrossRefGoogle Scholar
  9. [9]
    Watanabe, Y. et al.: Theory and Performance of a Jet Mixed Separator. J. Water SRT-Aqua 39(6) (1990) 387–395.Google Scholar
  10. [10]
    Watanabe, Y. et al.: Enhanced Flocculation/Sedimentation Process by a Jet Mixed Separator. Proc. of IAWQ/IWSA Joint Specialist Group on Particle Separation Workshop, Sapporo 1997, pp. 57–70.Google Scholar
  11. [11]
    Baylis, J.R.: Silicates as Aid to Coagulation. J. AWWA 29 (1937) 1355–1396.Google Scholar
  12. [12]
    Merrill, R.C., Spencer, R.W.: Gelation of Sodium Silicate. J. Phys. and Colloid Chem. 54(6) (1950) 806.CrossRefGoogle Scholar
  13. [13]
    Fory, P.J.: Molecular Weights and Intrinsic Viscosities of Polyisobutylenes. J. Am. Chem. Soc. 65 (1943) 372–382.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Y. Watanabe
    • 1
  • K. Hashimoto
    • 2
  • T. Hasegawa
    • 2
  • S. Kameda
    • 2
  • H. Suzuki
    • 1
  1. 1.Department of Environmental EngineeringHokkaido UniversitySapporoJapan
  2. 2.Suido Kiko Kaisha Ltd.Setagaya-ku, Tokyo 156Japan

Personalised recommendations