Effects of membrane fouling on N-nitrosamine rejection by nanofiltration and reverse osmosis membranes

Abstract

Open and solid symbol indicates the result of the first and second experiment, respectively. The impact of fouling on N-nitrosamine rejection by nanofiltration (NF) and reverse osmosis 2 (RO) membranes was investigated in this study. Membrane fouling was simulated using 3 tertiary treated effluent and several model fouling solutions (that contained sodium alginate, 4 bovine serum albumin, humic acid or colloidal silica) to elucidate the changes in rejection 5 behaviour of N-nitrosamines. In general, the rejection of N-nitrosamines increased when the 6 membranes were fouled by tertiary effluent. The rejection of small molecular weight N-7 nitrosamines was most affected by membrane fouling. In particular, the rejection of N-8 nitrosodimethylamine (NDMA) by the ESPA2 membrane increased from 34 to 73% after 9 membrane fouling caused by tertiary effluent. The results also indicate that the impact was 10 less apparent for the lowest permeability membrane (i.e., ESPAB), and the rejection of N-11 nitrosamines by the ESPAB membrane was over 82% regardless of membrane fouling. The 12 effect of membrane fouling caused by model foulants on N-nitrosamine rejection was 13 considerably less than that caused by tertiary effluent. Size exclusion chromatography 14 analyses revealed that the tertiary effluent contains a high fraction of low molecular weight (< 15 500 g/mol) organic substances. It appears that these low molecular weight foulants present in 16 the tertiary effluent can restrict the solute pathway within the active skin layer of membranes, 17 resulting in the observed increase of solute rejection. 18

Changes in surface properties and separation efficiency of a nanofiltration membrane after repeated fouling and chemical cleaning cycles

“…Once fouled, the membrane surface was covered with the foulant and the surface hydrophobicity of the fouled membrane reflects the hydrophobicity of the foulant itself [35]. Changes observed in the membrane surface hydrophobicity due to humic acids, sodium alginate and secondary treated effluent fouling are consistent with data previously reported by Fujioka et al [27]. Silica colloids are quite hydrophilic due to their negatively charged silanol groups [36].…”

“…The hydrodynamic diameter of the Ludox HS30 silica colloids was estimated to be approximately 9 nm [26]. By contrast, molecular weights of the humic acid and sodium alginate were in a range 12 -80 and 1 -100 kDa, respectively [27].…”

Removal of Emerging Contaminants for Water Reuse by Membrane Technology

“…This can also be supported by other experimental results using various model foulants in which the impact of model foulants (i.e. sodium alginate, humic acid, bovine serum albumin, colloidal silica) on N-nitrosamine rejection was minor or negligible [47]. These model foulants are larger in size than the free-volume hole-size of the membrane active skin layer and has a relatively narrow size distribution.…”

“…Fujioka et al [47] evaluated the effects of membrane fouling using tertiary treated wastewater and reported that membrane Fujioka et al [47] suggested that the increased rejections could have been caused by the restriction of compound pathway (e.g. free-volume holes of the active skin layer) with small foulants, improving the size exclusion effect on compound rejection.…”

A rapid and reliable technique for N -nitrosodimethylamine analysis in reclaimed water by HPLC-photochemical reaction-chemiluminescence

“…200 µL) will allow for detailed investigations of the fate of NDMA including NDMA formation and removal during water reclamation at laboratory scale. In fact, the limitation of providing a large number of samples for SPE-GC-MS/MS analysis significantly limited the number of sampling occasions in a previous laboratory-scale fouling study (Fujioka et al, 2013a). This study aimed to establish an HPLC-PR-CL analytical method that is fast and reliable for NDMA analysis during potable water reuse.…”