Journal of Korean Society on Water Environment (한국물환경학회지)

Korean Society on Water Environment (한국물환경학회)
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Sensitivity Analysis of Initial Pressure and Upper Control Limit on the Pressure Decay Test for Membrane Integrity Evaluation

압력손실시험을 이용한 막 완결성 평가에서 초기압력 및 UCL 도출인자 민감도 분석

  • Lee, Joohee (Civil, Environmental and Architectural Engineering Department, Korea University) ;
  • Hong, Seungkwan (Civil, Environmental and Architectural Engineering Department, Korea University) ;
  • Hur, Hyunchul (Watertreatment section, Waterworks Research Institute, Seoul Metropolitan Government) ;
  • Lee, Kwangjae (Watertreatment section, Waterworks Research Institute, Seoul Metropolitan Government) ;
  • Choi, Youngjune (Watertreatment section, Waterworks Research Institute, Seoul Metropolitan Government)
  • 이주희 (고려대학교 건축사회환경공학과) ;
  • 홍승관 (고려대학교 건축사회환경공학과) ;
  • 허현철 (서울시상수도연구원) ;
  • 이광제 (서울시상수도연구원) ;
  • 최영준 (서울시상수도연구원)
  • Received : 2008.07.23
  • Accepted : 2008.10.21
  • Published : 2008.11.30
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Abstract

Recently domestic drinking water industry has recognized membrane-based technology as a promising alternative for water treatment. To ensure successful application of membrane processes, the integrity of membrane systems should be maintained. According to US EPA guidance, the pressure decay test based on the bubble point theory is recommended to detect any membrane defection of which size is close to the smallest diameter of Cryptosporidium oocysts, $3{\mu}m$. Proper implementation of the pressure decay test is greatly affected by initial test pressure, and the interpretation of the test results is associated with upper control limit. This study is conducted to investigate various factors affecting determination of initial test prtessure and upper control limit, including membrane-based parameters such as pore shape correction factor, surface tension and contact angle, and system-based parameters, such as volumetric concentration factor and total volume of system. In this paper, three different hollow fibers were used to perform the pressure decay test. With identical initial test pressure applied, their pressure decay tendency were different from each other. This finding can be explained by the micro-structure disparity of those membranes which is verified by FESEM images of those membranes. More specifically, FESEM images revealed that three hollow fibers have asymmetry, deep finger, shallow finger pore shape, respectively. In addition, sensitivity analysis was conducted on five parameters mentioned above to elucidate their relation to determination of initial test pressure and upper control limit. In case of initial pressure calculation, the pore shape correction factor has the highest value of sensitivity. For upper control limit determination, system factors have greater impact compared to membrane-based parameters.

Keywords

Acknowledgement

Supported by : 환경부

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