Browsing by Author "Sanderson, R"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Restricted
    Measurement and modelling of organic fouling deposition in ultrafiltration by ultrasonic transfer signals and reflections.
    (Elsevier, 2002) Li, Jianxin; Sanderson, R; Hallbauer, D; Hallbauer-Zadorozhnaya, V Y
    The development of a non-destructive, real-time observation technique to detect and monitor fouling during liquid separation processes is of great importance to the development of strategies to improve operating conditions. In this study ultrasonic time-domain reflectometry (UTDR) was used to measure organic fouling, in real time, during ultrafiltration (UF) with polysulfone (PS) membranes. The feed solution was a paper-mill effluent, which contains breakdown products of lignin or lignosulphonate, from a wastewater treatment plant. An asymmetric, composite PS membrane can be detected by UTDR. Experimental results showed that the ultrasonic signal response can be used to monitor fouling-layer formation and growth on the membrane in real-time. Traditional flux measurements and analysis of the membrane surface by microscopy corroborated the UTDR results. Further, the differential signal developed indicate the state and progress of the fouling layer and gives warning of advanced fouling during operation. Moreover, a predictive modelling program — ultrasonic reflection (USRF) was developed to model the fouling deposits. This contributed to a better understanding of the fouling layer formation and its recognition during ultrasonic testing. This modelling was applied to model the density and thickness of a fouling layer on a membrane surface so as to predict the fouling behavior. The modelling results were in a good agreement with the actual observations.
  • Thumbnail Image
    Item
    Restricted
    Non-invasive visualization of the fouling of microfiltration membranes by ultrasonic time-domain reflectometry.
    (Elsevier, 2002) Li, J; Sanderson, R; Jacobs, E
    An ultrasonic time-domain reflectometry (UTDR) technique has been applied to the non-invasive study of fouling in microfiltration (MF) membrane modules operating at 100 kPa. The experimental results show a good correspondence between the UTDR signal response from the membranes and the development of a fouling layer on the membrane surface. The ultrasonic technique could effectively detect fouling-layer initiation and growth on the membrane in real-time. For experiments conducted at different axial velocities, ranging from 1.83 to 23.0 cm/s (Re from 65.4 to 811), a sequential mode fouling layer growth was observed. The UTDR technique was capable of distinguishing individual modes of growth. The data also suggest the formation of a second echo in the time domain at 100 kPa operating pressure. Therefore, the UTDR technique was used to quantify the thickness of a fouling layer. The non-invasive UTDR visualization of the fouling on the membrane surface was supported by “post-mortem” SEM analysis of the membrane surface. The UTDR technique can be more suitable for non-invasive visualization of the fouling in MF system.