Effects of concentration polarization, temperature and pressure on ultrasound detection of inorganic fouling and cleaning in a spiral-wound membrane module

Abstract

Ultrasonic time-domain reflectometry (UTDR) involves passing an acoustic wave through a medium and analyzing the reflected waveform. In this study, UTDR is used to track the waveform peaks reflected from the outer and inner membranes in the outermost feed channel in a Koch 2521 spiral-wound module. The UTDR amplitude is shown to be more sensitive to fouling than the transit (arrival) time. The local (point) measurement provided by UTDR is shown to be advantageous since its location can be optimized for early fouling detection. Concentration polarization is shown not to compromise UTDR. This is an advantage relative to flux decline that responds to both fouling and concentration polarization. The UTDR amplitude is found to increase with increasing temperature and decreasing pressure. This is explained by the effect these parameters have on the crystallization rate that changes the fouling layer morphology and thereby the reflected UTDR waveform. This study underscores the importance of establishing a UTDR reference surface suitable for unambiguous detection of fouling. It also emphasizes the necessity for good temperature and pressure control during UTDR measurements as well as a more comprehensive understanding of the effects of operating condition changes on the ultrasound waveforms.

Polymeric membranes for produced water treatment: an overview of fouling behavior and its control

“…Complex fouling of polymeric membrane by various pollutants between the active layer of membrane surface and foulant molecules requires harsh chemical and/or thermal treatment to remove, as the result of both abrasion and oxidation are irreversible damages that make impossible to recover the reference performance of original membranes (Drews 2010, Pena et al 2013. Cleaning strategies to control membrane fouling such as proper process design, operating condition, membrane cleaning by ultrasonic technique, cleaning by mechanical means, and hydraulic cleaning are all described well in the literature (Hilal et al 2005, Ang et al 2011, Sy Thuy and Roddick 2011, Chai et al 2012, Hajibabania et al 2012, Isa et al 2012, Linares et al 2012, Naim et al 2012, Agarwal et al 2013, Lujan-Facundo et al 2013, Nam et al 2013, Ramon et al 2013, Wan et al 2013, 2014, Woo et al 2013, 2014, Corbaton-Baguena et al 2014). …”

Development of novel monitors for early detection of fouling in reverse osmosis systems

“…Measurement of thickness changes has been proven for various processes such as the evaporative casting of polymeric films (Kools et al, 1998), membrane compaction owing to high-pressure (Peterson et al, 1998;Aerts et al, 2001), and cake layer growth of various foulants (Mairal et al, 1999;Mairal et al, 2000;Li et al, 2002a;Li et al, 2002b;Li and Sanderson, 2002;Xiu et al, 2002;Li et al, 2005b;Chai et al, 2007;Li et al, 2007;Silalahi et al, 2009;Chai et al, 2012;Li et al, 2012;Lu et al, 2012;Mizrahi et al, 2012;Sim et al, 2012a;Sim et al, 2013b;Taheri et al, 2013). Non-invasive measurement of membrane fouling and cleaning has also been done using UTDR (Mairal et al, 1999;Mairal et al, 2000;Li and Sanderson, 2002;Sanderson et al, 2002;Chai et al, 2007;Lu et al, 2012;Mizrahi et al, 2012;Sim et al, 2012a;Sim et al, 2013b;Chai et al, 2012). Large scale applications have been demonstrated by using UTDR to study commerical spiral wound RO modules (Chai et al, 2007;Chai et al, 2012).…”

“…Non-invasive measurement of membrane fouling and cleaning has also been done using UTDR (Mairal et al, 1999;Mairal et al, 2000;Li and Sanderson, 2002;Sanderson et al, 2002;Chai et al, 2007;Lu et al, 2012;Mizrahi et al, 2012;Sim et al, 2012a;Sim et al, 2013b;Chai et al, 2012). Large scale applications have been demonstrated by using UTDR to study commerical spiral wound RO modules (Chai et al, 2007;Chai et al, 2012). Hence, UTDR possess the potential to observe fouling in-situ, in real-time and non-destructively.…”

“…The permeate support used for all experiments was the product spacer with a thickness of about 0.2 mm used in a spiral wound reverse osmosis module. The foulant layer thickness was calculated using Equation 2.12 in section 2.4.1 of Chapter 2 for which the sound velocity was assumed to be 1500m/s similar to that of water (Sim et al, 2012a;Chai et al, 2012).…”

In situ investigation of combined organic and colloidal fouling for nanofiltration membrane using ultrasonic time domain reflectometry

“…The results showed a good correspondence between the change of ultrasonic signal amplitude and the development/removal of the scaling layer. Chai et al [12,13] employed UTDR to study inorganic fouling and cleaning of commercial spiralwound modules. In their studies, four particular peaks which emanated from specific surfaces were selected from the waveform responses as the observed signals to track their changes as the fouling progressed.…”