title: Bacterial community structure and variation in a full-scale seawater desalination plant for drinking water production.
abstract: Microbial processes inevitably play a role in membrane-based desalination plants, mainly recognized as membrane biofouling. We assessed the bacterial community structure and diversity during different treatment steps in a full-scale seawater desalination plant producing 40,000 m(3)/d of drinking water. Water samples were taken over the full treatment train consisting of chlorination, spruce media and cartridge filters, de-chlorination, first and second pass reverse osmosis (RO) membranes and final chlorine dosage for drinking water distribution. The water samples were analyzed for water quality parameters (total bacterial cell number, total organic carbon, conductivity, pH, etc.) and microbial community composition by 16S rRNA gene pyrosequencing. The planktonic microbial community was dominated by Proteobacteria (48.6%) followed by Bacteroidetes (15%), Firmicutes (9.3%) and Cyanobacteria (4.9%). During the pretreatment step, the spruce media filter did not impact the bacterial community composition dominated by Proteobacteria. In contrast, the RO and final chlorination treatment steps reduced the Proteobacterial relative abundance in the produced water where Firmicutes constituted the most dominant bacterial group. Shannon and Chao1 diversity indices showed that bacterial species richness and diversity decreased during the seawater desalination process. The two-stage RO filtration strongly reduced the water conductivity (>99%), TOC concentration (98.5%) and total bacterial cell number (>99%), albeit some bacterial DNA was found in the water after RO filtration. About 0.25% of the total bacterial operational taxonomic units (OTUs) were present in all stages of the desalination plant: the seawater, the RO permeates and the chlorinated drinking water, suggesting that these bacterial strains can survive in different environments such as high/low salt concentration and with/without residual disinfectant. These bacterial strains were not caused by contamination during water sample filtration or from DNA extraction protocols. Control measurements for sample contamination are important for clean water studies.
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Belila
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia; Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: El-Chakhtoura
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia.
authors.forename: N
authors.initials: N
authors.lastname: Otaibi
authors.affiliation: Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Muyzer
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia.
authors.forename: G
authors.initials: G
authors.lastname: Gonzalez-Gil
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia.
authors.forename: P E
authors.initials: PE
authors.lastname: Saikaly
authors.affiliation: Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: M C M
authors.initials: MCM
authors.lastname: van Loosdrecht
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia; Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands. Electronic address: j.s.vrouwenvelder@tudelft.nl.
authors.forename: J S
authors.initials: JS
authors.lastname: Vrouwenvelder
mesh_terms: D002713:Chlorine / Q000737:chemistry; D004269:DNA, Bacterial / Q000302:isolation & purification; D060766:Drinking Water / Q000382:microbiology*; D005374:Filtration; D008567:Membranes, Artificial; D009995:Osmosis; D020560:Proteobacteria / Q000302:isolation & purification*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D004269:DNA, Bacterial; D060766:Drinking Water; D008567:Membranes, Artificial; D012336:RNA, Ribosomal, 16S; D002713:Chlorine
keywords: 16S rRNA gene pyrosequencing; Bacterial population; Membrane based drinking water production; Reverse osmosis; Sample contamination control; Seawater desalination