Membrane Characterization by Ultrasonic Time-Domain Reflectometry

Abstract Local scour is a growing cause of bridge failure in the United States and around the world. In the next century, the effects of climate changes will make more bridges susceptible to scour failure more than ever before. This study aims to harness the spatially continuous monitoring capabilities of ultrasonic time-domain reflectometry to detect a soil interface for the purposes of scour monitoring. In this study, a long, slender plate is coupled with two flexible piezoelectric devices that propagate Lamb waves along the length of the plate to form the scour sensor. The sensor was tested for sensitivity to external pressure using metal weights, and was able to detect the position of the pressure up at a length of up to ~ 20 feet. The sensor was tested under simulated scour conditions, being buried in sand at various depths. The results show that the Lamb wave scour sensor is capable of reliably detecting a soil interface at 1 ft intervals. The scour sensor was also able to detect uncompacted soil interfaces, which is important considering the issue of scour hole refill following an extreme event.

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Real-time measurement of inorganic fouling of RO desalination membranes using ultrasonic time-domain reflectometry

Journal of Membrane Science ◽

10.1016/s0376-7388(99)00058-7 ◽

1999 ◽

Vol 159 (1-2) ◽

pp. 185-196 ◽

Cited By ~ 120

Author(s):

Anurag P Mairal ◽

Alan R Greenberg ◽

William B Krantz ◽

Leonard J Bond

Keyword(s):

Real Time ◽

Time Domain ◽

Time Measurement ◽

Time Domain Reflectometry ◽

Real Time Measurement ◽

Ultrasonic Time ◽

Inorganic Fouling

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In situ monitoring of wastewater biofilm formation process via ultrasonic time domain reflectometry (UTDR)

Chemical Engineering Journal ◽

10.1016/j.cej.2017.11.043 ◽

2018 ◽

Vol 334 ◽

pp. 2134-2141 ◽

Cited By ~ 14

Author(s):

Jinfeng Wang ◽

Hongqiang Ren ◽

Xianhui Li ◽

Jianxin Li ◽

Lili Ding ◽

...

Keyword(s):

Time Domain ◽

Formation Process ◽

Biofilm Formation ◽

Time Domain Reflectometry ◽

In Situ Monitoring ◽

Ultrasonic Time

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Monitoring of CaSO4 deposition behaviors on biofilm during nanofiltration via ultrasonic time-domain reflectometry (UTDR)

Water Science & Technology ◽

10.2166/wst.2010.165 ◽

2010 ◽

Vol 61 (11) ◽

pp. 2853-2861 ◽

Cited By ~ 7

Author(s):

Y. L. Hou ◽

J. X. Li ◽

Y. N. Gao ◽

X. C. Xu ◽

Y. Cai ◽

...

Keyword(s):

Time Domain ◽

Pressure Effect ◽

Membrane Surface ◽

Time Domain Reflectometry ◽

Sem Images ◽

Differential Signal ◽

Flux Decline ◽

Ultrasonic Time ◽

Ultrasonic Measurements ◽

Non Destructive

The ultrasonic time-domain reflectometry (UTDR) as a non-destructive real-time method was employed to monitor the CaSO4 deposition behaviors on biofilm during nanofiltration (NF). Two parallel experiments were performed to compare the different behaviors of CaSO4 deposition with and without biofilm on the membrane. Results showed that the flux decline during combined fouling was slower than that in case of CaSO4 fouling alone. The Ca2 + rejection obtained with biofilm was higher than that without. A larger acoustic differential signal obtained by UTDR in the combined fouling revealed a denser and thicker layer formed on the membrane surface. Furthermore, the amount of CaSO4 deposition on the biofouled membrane was more than that on non-biofouled membrane as a result of microorganisms as crystal nucleus to induce CaSO4 crystallization and deposition. SEM images indicate that the CaSO4 crystals deposited in order on the non-biofouled membrane, whereas on the biofouled membrane they were embedded in the biofilm. The denser and thicker fouling layer formed with biofilm was impermeable, resulting in a high Ca2 + rejection. The complexation of Ca with polysaccharide in biofilm would eliminate the cake-enhanced osmotic pressure effect leading to a slow flux decline. To sum up, the independent measurements corroborate the ultrasonic measurements.

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