Accelerated ageing of PES UF membranes

摘要

In this research, membrane life-time is evaluated by means of accelerated ageing experiments. In the performed experiments three main ageing factors are varied, namely mechanical stress (back-pulsing), chemicals exposure (cleaning with oxidative chemicals) and the membrane fouling status. A pressure-pulse-unit (PPU) was used to simulate standard membrane operation in an accelerated way. The PPU can be used to back-pulse cleaning agents with a frequency of around twenty to thirty times per minute through a membrane module. During the back-pulses, the membranes are frequently tested for integrity by means of permeability measurements, pressure decay test and bubble tests. The magnitude of a pressure pulse, the concentration of cleaning agent and the fouling status of the membrane were varied. The outcomes of the experiments show that the membrane fouling status is a major ageing factor. Clean membranes easily withstand 300.000 back-pulses with 1000 ppm NaClO at 2.0 bars, respectively, 10 years of operation and 350.000 ppm.h sodium hypo chlorite exposure. The collected data will be used in the further development of a mathematical membrane-life-time model that predicts the probability of membrane failure.