Monitoring the membrane integrity for membrane damage detection used for water treatment: “Lab to scale-up application”

Abstract

This study aims to develop a methodology that minimizes measurement errors in the pressure decay test (PDT) used for detecting membrane damage, particularly as the capacity of membrane filtration facilities increases. In the initial step of the PDT procedure, the most critical factor is the establishment of complete air–liquid conversion (CALC) across the membrane boundary, which is essential for accurate detection of membrane defects. Experiments were conducted on lab., pilot (full), and unit scales to evaluate CALC by applying the initial set pressure (Ptest) and the corresponding injected accumulative gas volume (IAGV). While CALC was successfully achieved at both the lab and full scales, the unit-scale system (26 modules) reached the Ptest without achieving CALC, and the air–liquid conversion rate (ALCR) was only about 77 %. To address this issue, controlling the air injection rate improved the ALCR to 0 %, indicating complete conversion. Therefore, when Ptest is determined using the lab-scale membrane module, the IAGV should be applied as the control parameter in the unit-scale system to detect membrane damage more effectively and minimize contaminant leakage during PDT operations.