Control of the CaCO3 Saturation Index Parameters for Protecting the Corrosion of Waterworks Pipe

상수도관 부식방지를 위한 탄산칼슘 포화지수(LI) 인자 제어에 관한 연구

  • Park, Young-Bok (Department of Chemical Engineering, Hanyang University) ;
  • Kong, Sung-Ho (Department of Chemical Engineering, Hanyang University)
  • 박영복 (한양대학교 화학공학과) ;
  • 공성호 (한양대학교 화학공학과)
  • Received : 2005.01.03
  • Accepted : 2005.04.12
  • Published : 2005.06.10

Abstract

Calcium Carbonate Saturation Index (LI: Langelier Index), an indicator of $CaCO_3(s)$ saturation, indicates corrosiveness of drinking water and it has been used to monitor drinking water conditions in USA, E.U, and Japan. The objective of this research was to measure LI parameters including water temperature, pH, total alkalinity, calcium ion concentration, and electric conductivity, and to evaluate possibility of using LI in domestic system. Results showed that water temperature varied from 2.0 to $26^{\circ}C$ during 15 months, indicating an average annual temperature of $23.9^{\circ}C$. Total alkalinity was from 20 to 45 mg/L. The concentration difference between total alkalinity and $HCO_3{^-}$ value was hardly observed; the concentration of total alkalinity can be replaced by that of $HCO_3{^-}$. Tap water had a medium corrosiveness since LI values were from 2.0 to 0.5. To reduce the corrosiveness and to increase LI values of drinking water, the results of this study showed that chemicals such as $Ca(OH)_2$, $CaCO_3$, NaOH, or $NaHCO_3$ should be added to water treatment plants.

Acknowledgement

Supported by : 서울특별시 상수도연구소

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