APPLICATION OF OPTICAL FIBER SENSOR FOR DETECTION OF HOLLOW-FIBER MEMBRANE BREAKAGE USED FOR WATER PURIFICATION

Abstract

 This study aimed to develop a non-destructive method of hollow-fiber membrane breakage detection in water treatment processes using optical fiber sensors. Ten FBG pressure sensors were deployed in a membrane housing, wherein hollow-fiber membranes with varied numbers of cut-off at the inlet and outlet sides of the membrane were installed and the membrane filtration system was operated in a dead-end mode. It was found that the sensitivity of pressure change detection was higher for the conventional pressure gauge than the FBG sensors possibly because two pressure gauges were installed at the inlet and outlet sides of the membrane module, whereas FBG sensors were used for the measurement of the average pressure change in the membrane housing. The predicted filtration pressure reduction by a water flow model within the failed membrane module agreed well with the pressure decreases for the membranes cut at the inlet side, but predicted pressure reduction by the model was greater than the experimental results of membranes cut at the outlet side of the membrane module. The sensitivity of membrane failure detection was significantly improved by using the pressure slope between two neighboring FBG sensors as an indicator. The pressure slope indicator also showed possibility of detecting the position of membrane failure within a membrane housing.