Characterization of Inorganic Membrane Fouling

Fouling refers to the deposition of dissolved solutes, particulates, and coUoids on a membrane. Fouling usually is inferred from a decline in permeate flux and quality. However, permeate flux and quality can decline for reasons other than fouling, such as concentration polarization or membrane compaction. Moreover, permeate flux and quality do not provide any information on local conditions in a membrane module that is, one might want to arrest fouling at its inception, which usually occurs before signiflcant changes in permeate flux or quality occur. 

First Membrane Layer Second Membrane Layer Third Membrane Layer 

MEMBRANE CHARACTERIZATION BY ULTRASONIC TIME-DOMAIN REFLECTOMETRY 

Zhang et al. (2003) developed an alternative method for coping with the complex multiple reflections in spiral-wound membrane modules. They defined an amplitude shift factor Qa and an arrival time shift factor Qt that characterize the entire reflected waveform response or selected regions of it as follows  

The arrival time and amplitude shift factors provide convenient metrics for use in combination with the fouling meter patented by Bond et al. (2000). That is, a microprocessor can be incorporated into the fouling meter to determine these two metrics in order to indicate the condition of a membrane module. 

---