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.
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.
Water Res. 2016 May 1;94:62-72. doi: 10.1016/j.watres.2016.02.039. Epub 2016 Feb 18.
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.
微生物过程不可避免地在膜基海水淡化厂中发挥作用，主要表现为膜生物污染。我们评估了在生产 40,000 m(3)/d 饮用水的全规模海水淡化厂的不同处理步骤中细菌群落结构和多样性。在包括氯化、云杉介质和筒式过滤器、脱氯、第一和第二道反渗透 (RO) 膜以及最终饮用水分配氯剂量的整个处理过程中采集水样。通过 16S rRNA 基因焦磷酸测序分析水样的水质参数（总细菌细胞数、总有机碳、电导率、pH 值等）和微生物群落组成。浮游微生物群落主要由变形菌门（48.6%）主导，其次是拟杆菌门（15%）、厚壁菌门（9.3%）和蓝细菌门（4.9%）。在预处理步骤中，云杉介质过滤器对以变形菌门为主导的细菌群落组成没有影响。相比之下，RO 和最终氯化处理步骤降低了生产水中的变形菌相对丰度，其中厚壁菌门构成最主要的细菌群。香农和 Chao1 多样性指数表明，海水淡化过程中细菌物种丰富度和多样性降低。两级 RO 过滤强烈降低了水的电导率（>99%）、TOC 浓度（98.5%）和总细菌细胞数（>99%），尽管 RO 过滤后水中仍发现一些细菌 DNA。大约 0.25%的总细菌操作分类单元 (OTU) 存在于海水淡化厂的所有阶段：海水、RO 渗透物和氯化饮用水中，这表明这些细菌株可以在不同的环境中生存，例如高/低盐浓度和有/无残留消毒剂。这些细菌株不是由于水样过滤或 DNA 提取方案的污染造成的。对于清洁水研究，控制样品污染的测量非常重要。
