A comparison of alginate fouling in forward osmosis (FO) with that in reverse osmosis (RO) was made. A key experimental finding, corroborated by membrane autopsies, was that FO is essentially more prone to fouling than RO, which is opposite to a common claim in the literature where deductions on fouling are often based solely on the water flux profiles. Our theoretical analysis shows that, due to a decrease in the intensity of internal concentration polarization (ICP), and thus an increase in the effective osmotic driving force during FO fouling tests, the similarity of experimental water flux profiles for FO and RO is in accordance with there being greater fouling in FO than RO. The specific foulant resistance for FO was also found to be greater than that for RO. Possible explanations are discussed and these include the influence of reverse solute diffusion from draw solution. Whilst this explanation regarding specific foulant resistance is dependent on the draw solution properties, the finding of greater overall foulant accumulation in FO is considered to be a general finding. Additionally, the present study did not find evidence that hydraulic pressure in RO plays a critical role in foulant layer compaction. Overall this study demonstrated that although FO has higher fouling propensity, it offers superior water flux stability against fouling. For certain practical applications this resilience may be important.

. (2018) 'Analysis of the in uence of module construction upon forward osmosis performance. ', Desalination., Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe potential of a commercial forward osmosis (FO) module to recover water from NEWater brine, an RO retentate, was assessed by taking an innovative approach to obtaining the mass transfer coefficients. The performance comparison of the spiral wound (S-W) FO module with that of the flat sheet laboratory unit suggests that the winding involved in S-W construction can adversely affect performance; the values for the S-W mass transfer coefficients were half of those expected. This firstof-its-kind performance comparison utilised coupons of the membrane and spacers taken from the module. The module was used both in the conventional manner for FO and in the reverse manner with the active layer facing the draw solution. Estimates of membrane parameters and mass transfer coefficients experiments for the two orientations were obtained using pure water, 10mM and 25mM NaCl solution on the feed side and 1M NaCl as draw solution. The fouling potential of NEWater brine per se was found to be low. These are the first results with a S-W module that suggest potential for this niche application; nevertheless the level of the water flux through the S-W module clearly indicates that industrial applications of S-W FO will be constrained to special cases.