Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), 6900, Thuwal 23955, Saudi Arabia.
Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), 6900, Thuwal 23955, Saudi Arabia; Environmental Science and Engineering Program, Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), 6900, Thuwal 23955, Saudi Arabia.
Water Res. 2022 Sep 1;223:118983. doi: 10.1016/j.watres.2022.118983. Epub 2022 Aug 14.
Biofouling is a hurdle of seawater desalination that increases water costs and energy consumption. In membrane distillation (MD), biofouling development is complicated due to the temperature effect that adversely affects microbial growth. Given the high relevance of MD to regions with abundant warm seawater, it is essential to explore the biofouling propensity of microbial communities with higher tolerance to elevated temperature conditions. This study presents a comprehensive analysis of the spatial and temporal biofilm distribution and associated membrane fouling during direct contact MD (DCMD) of the Red Sea water. We found that structure and composition of the biofilm layer played a significant role in the extent of permeate flux decline, and biofilms that built up at 45°C had lower bacterial concentration but higher extracellular polymeric substances (EPS) content as compared to biofilms that formed at 55 °C and 65°C. Pore wetting and bacterial passage to the permeate side were initially observed but slowed down as operating time increased. Intact cells in biofilms dominated over the damaged cells at any tested condition emphasizing the high adaptivity of the Red Sea microbial communities to elevated feed temperatures. A comparison of microbial abundance revealed a difference in bacterial distribution between the feed and biofilm samples. A shift in the biofilm microbial community and colonization of the membrane surface with thermophilic bacteria with the feed temperature increase was observed. The results of this study improve our understanding of biofouling propensity in MD that utilizes temperature-resilient feed waters.
生物污损是海水淡化的一个障碍，会增加水成本和能源消耗。在膜蒸馏（MD）中，由于温度对微生物生长的不利影响，生物污损的发展变得复杂。鉴于 MD 与拥有丰富温暖海水的地区高度相关，因此探索对高温条件具有更高耐受性的微生物群落的生物污损倾向至关重要。本研究全面分析了红海海水直接接触膜蒸馏（DCMD）过程中生物膜的时空分布和相关的膜污染。我们发现，生物膜层的结构和组成对渗透通量下降的程度起着重要作用，与在 55°C 和 65°C 下形成的生物膜相比，在 45°C 下形成的生物膜具有较低的细菌浓度但较高的胞外聚合物物质（EPS）含量。在操作时间增加的情况下，最初观察到膜孔润湿和细菌向渗透侧迁移，但随后迁移速度减慢。在任何测试条件下，生物膜中的完整细胞都超过受损细胞，这强调了红海微生物群落对升高的进料温度的高度适应性。对微生物丰度的比较表明，在进料和生物膜样品之间存在细菌分布的差异。随着进料温度的升高，观察到生物膜微生物群落的转变和嗜热细菌在膜表面的定殖。本研究的结果提高了我们对利用温度弹性进料水的 MD 中生物污损倾向的理解。
