title: Impact of spacer thickness on biofouling in forward osmosis.
abstract: Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux.
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia; Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology Delft, The Netherlands. Electronic address: rodrigo.valladares@kaust.edu.sa.
authors.forename: R
authors.initials: R
authors.lastname: Valladares Linares
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia.
authors.forename: Sz S
authors.initials: SS
authors.lastname: Bucs
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia.
authors.forename: M
authors.initials: M
authors.lastname: AbuGhdeeb
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia.
authors.forename: G
authors.initials: G
authors.lastname: Amy
authors.affiliation: King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia; Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology Delft, The Netherlands; Wetsus, Centre of Excellence for Sustainable Water Technology, Leeuwarden, The Netherlands.
authors.forename: J S
authors.initials: JS
authors.lastname: Vrouwenvelder
mesh_terms: D057219:Biofouling; D005374:Filtration; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D009995:Osmosis; D009997:Osmotic Pressure; D012623:Seawater / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000295:instrumentation*; D062065:Wastewater / Q000032:analysis; D018508:Water Purification / Q000295:instrumentation*
chemical_list: D062065:Wastewater
keywords: Biofouling impact reduction; Feed spacer; Forward osmosis; Seawater desalination; Wastewater reuse