TY - JOUR
T1 - Biofouling removal in spiral-wound nanofiltration elements using two-phase flow cleaning
AU - Wibisono, Y.
AU - El Obied, K.E.
AU - Cornelissen, E.R.
AU - Kemperman, A.J.B.
AU - Nijmeijer, K.
N1 - Funding Information:
This work was performed in the cooperation framework of Wetsus, centre of excellence for sustainable water technology ( www.wetsus.nl ). Wetsus is co-funded by the Dutch Ministry of Economic Affairs and Ministry of Infrastructure and Environment , the European Union Regional Development Fund , the Province of Fryslân, and the Northern Netherlands Provinces. The authors thank the participants of the research theme Clean Water Technology for fruitful discussions and their financial support. In addition the authors would especially like to thank Herman Teunis and Ineke Pünt (University of Twente) for their help with SEM imaging. Adam Wexler (Wetsus) is acknowledged for his great help with OCT.
Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2015/2/1
Y1 - 2015/2/1
N2 - Biofouling has detrimental effects on the feed channel pressure drop and the permeate flux in high-pressure membrane processes such as NF and RO. Two-phase flow cleaning is a chemical-free technique that is able to remove such biofilms. This paper presents a study into the effects of the gas/liquid ratio, feed spacer geometry, applied pressure and liquid velocity on the efficiency of two-phase flow cleaning in spiral-wound nanofiltration elements. A high-speed camera, optical coherence tomography and scanning electron microscopy were used to study biofouling and its removal. Our results show that two conditions must be met to ensure that a sufficiently high shear force is applied to biofilms on membrane and spacer surfaces. A good bubble distribution in the channel is the first requirement. While it is mainly the structure of the feed spacer that controls bubble flow and bubble size, a minimum gas/liquid ratio of 0.5 is necessary to achieve a good bubble distribution. The second condition is the use of a sufficiently high liquid velocity during cleaning. The bubble velocity was found to be 3.5-5.5 times as high as the used liquid velocity, and responsible for a marked improvement in the flux recovery.
AB - Biofouling has detrimental effects on the feed channel pressure drop and the permeate flux in high-pressure membrane processes such as NF and RO. Two-phase flow cleaning is a chemical-free technique that is able to remove such biofilms. This paper presents a study into the effects of the gas/liquid ratio, feed spacer geometry, applied pressure and liquid velocity on the efficiency of two-phase flow cleaning in spiral-wound nanofiltration elements. A high-speed camera, optical coherence tomography and scanning electron microscopy were used to study biofouling and its removal. Our results show that two conditions must be met to ensure that a sufficiently high shear force is applied to biofilms on membrane and spacer surfaces. A good bubble distribution in the channel is the first requirement. While it is mainly the structure of the feed spacer that controls bubble flow and bubble size, a minimum gas/liquid ratio of 0.5 is necessary to achieve a good bubble distribution. The second condition is the use of a sufficiently high liquid velocity during cleaning. The bubble velocity was found to be 3.5-5.5 times as high as the used liquid velocity, and responsible for a marked improvement in the flux recovery.
KW - Biofouling
KW - Nanofiltration
KW - Optical coherence tomography
KW - Spiral-wound membrane
KW - Two-phase flow cleaning
KW - 2023 OA procedure
UR - http://www.scopus.com/inward/record.url?scp=84908610877&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2014.10.016
DO - 10.1016/j.memsci.2014.10.016
M3 - Article
SN - 0376-7388
VL - 475
SP - 131
EP - 146
JO - Journal of membrane science
JF - Journal of membrane science
ER -