The importance of laboratory water quality for studying initial bacterial adhesion during NF filtration processes

TY - JOUR

T1 - The importance of laboratory water quality for studying initial bacterial adhesion during NF filtration processes

AU - Semião, A. J.C.

AU - Habimana, O.

AU - Cao, H.

AU - Heffernan, R.

AU - Safari, A.

AU - Casey, E.

N1 - Funding Information: This research was supported by the European Research Council (ERC) , project 278530, funded under the EU Framework Programme 7 and also with the financial support of Science Foundation Ireland under Grant Number “ SFI 11/RFP.1/ENM/3145. The authors would like to thank Dr. Dennis Dowling and the Surface Engineering research group at UCD. We thank Dr. Ian Reid of the NIMAC microscopy platform UCD. We thank Mr. Pat O'Halloran for his invaluable technical assistance, and Mr. Liam Morris for the construction of the MFS devices.

PY - 2013/5/15

Y1 - 2013/5/15

N2 - Biofouling of nanofiltration (NF) and reverse osmosis (RO) membranes for water treatment has been the subject of increased research effort in recent years. A prerequisite for undertaking fundamental experimental investigation on NF and RO processes is a procedure called compaction. This involves an initial phase of clean water permeation at high pressures until a stable permeate flux is reached. However water quality used during the compaction process may vary from one laboratory to another. The aim of this study was to investigate the impact of laboratory water quality during compaction of NF membranes. A second objective was to investigate if the water quality used during compaction influences initial bacterial adhesion. Experiments were undertaken with NF 270 membranes at 15bar for permeate volumes of 0.5L, 2L, and 5L using MilliQ, deionized or tap water. Membrane autopsies were performed at each permeation point for membrane surface characterisation by contact angle measurements, profilometry, and scanning electron microscopy. The biological content of compacted membranes was assessed by direct epi-fluorescence observation following nucleic acid staining. The compacted membranes were also employed as substrata for monitoring the initial adhesion of Ps. fluorescens under dynamic flow conditions for 30min at 5min intervals. Compared to MilliQ water, membrane compaction using deionized and tap water led to decreases in permeate flux, increase in surface hydrophobicity and led to significant build-up of a homogeneous fouling layer composed of both living and dead organisms (>106cellscm-2). Subsequent measurements of bacterial adhesion resulted in cell loadings of 0.2×105, 1.0×105cellscm-2 and 2.6×105cellscm-2 for deionized, tap water and MilliQ water, respectively. These differences in initial cell adhesion rates demonstrate that choice of laboratory water can significantly impact the results of bacterial adhesion on NF membranes. Standardized protocols are therefore needed for the fundamental studies of bacterial adhesion and biofouling formation on NF and RO membrane. This can be implemented by first employing pure water during all membrane compaction procedures and for the modelled feed solutions used in the experiment.

AB - Biofouling of nanofiltration (NF) and reverse osmosis (RO) membranes for water treatment has been the subject of increased research effort in recent years. A prerequisite for undertaking fundamental experimental investigation on NF and RO processes is a procedure called compaction. This involves an initial phase of clean water permeation at high pressures until a stable permeate flux is reached. However water quality used during the compaction process may vary from one laboratory to another. The aim of this study was to investigate the impact of laboratory water quality during compaction of NF membranes. A second objective was to investigate if the water quality used during compaction influences initial bacterial adhesion. Experiments were undertaken with NF 270 membranes at 15bar for permeate volumes of 0.5L, 2L, and 5L using MilliQ, deionized or tap water. Membrane autopsies were performed at each permeation point for membrane surface characterisation by contact angle measurements, profilometry, and scanning electron microscopy. The biological content of compacted membranes was assessed by direct epi-fluorescence observation following nucleic acid staining. The compacted membranes were also employed as substrata for monitoring the initial adhesion of Ps. fluorescens under dynamic flow conditions for 30min at 5min intervals. Compared to MilliQ water, membrane compaction using deionized and tap water led to decreases in permeate flux, increase in surface hydrophobicity and led to significant build-up of a homogeneous fouling layer composed of both living and dead organisms (>106cellscm-2). Subsequent measurements of bacterial adhesion resulted in cell loadings of 0.2×105, 1.0×105cellscm-2 and 2.6×105cellscm-2 for deionized, tap water and MilliQ water, respectively. These differences in initial cell adhesion rates demonstrate that choice of laboratory water can significantly impact the results of bacterial adhesion on NF membranes. Standardized protocols are therefore needed for the fundamental studies of bacterial adhesion and biofouling formation on NF and RO membrane. This can be implemented by first employing pure water during all membrane compaction procedures and for the modelled feed solutions used in the experiment.

KW - Cell adhesion

KW - Compaction

KW - Nanofiltration

KW - Water quality

UR - http://www.scopus.com/inward/record.url?scp=84876134850&partnerID=8YFLogxK

U2 - 10.1016/j.watres.2013.03.020

DO - 10.1016/j.watres.2013.03.020

M3 - 文章

C2 - 23541307

AN - SCOPUS:84876134850

SN - 0043-1354

VL - 47

SP - 2909

EP - 2920

JO - Water Research

JF - Water Research

IS - 8

ER -