Gao Zeyuan, Chen Qiuying, Song Xiaolan, Wang Jingwei, Cai Weiwei
School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China.
School of Environment, Beijing Normal University, Beijing 100875, China.
Membranes (Basel). 2022 Sep 23;12(10):920. doi: 10.3390/membranes12100920.
Ultrafiltration is widely used to treat various environmental waters, and on-line membrane cleaning with various chemical reagents is frequently employed to sustain the filtration flux. However, the residue of cleaning agents in the ultrafiltration system is unavoidable, which may affect microbiological properties and biofilm formation during the next-round filtration. By investigating the changes in microbial characteristics, and their biofouling behaviors after exposure to HCl, NaOH, NaClO, citric acid (CA), and sodium dodecyl sulfonate (SDS), this study fills a knowledge gap in microbial responses to various types of chemical cleaning agents in an ultrafiltration system. The result shows that HCl, NaOH, and NaClO affect the bacterial properties and subsequent attachment on the membrane surface, while CA and SDS have no obvious influence on microorganisms. Specifically, HCl, NaOH, and NaClO reduce the hydrophobicity and mean size of suspended microorganisms, increase the extracellular polymeric substances (EPS) release, and trigger intracellular reactive oxygen species (ROS) generation, resulting in the death of a large quantity of microorganisms. Due to the self-protecting strategy, plenty of living cells aggregate on the membrane surface and form a cake layer with a stratified structure, causing more severe membrane biofouling.
超滤被广泛用于处理各种环境水体，并且经常采用用各种化学试剂进行在线膜清洗来维持过滤通量。然而，清洗剂在超滤系统中的残留是不可避免的，这可能会影响下一轮过滤过程中的微生物特性和生物膜形成。通过研究暴露于盐酸、氢氧化钠、次氯酸钠、柠檬酸（CA）和十二烷基磺酸钠（SDS）后微生物特性的变化及其生物污染行为，本研究填补了超滤系统中微生物对各种类型化学清洗剂反应方面的知识空白。结果表明，盐酸、氢氧化钠和次氯酸钠会影响细菌特性以及随后在膜表面的附着，而柠檬酸和十二烷基磺酸钠对微生物没有明显影响。具体而言，盐酸、氢氧化钠和次氯酸钠会降低悬浮微生物的疏水性和平均大小，增加胞外聚合物（EPS）的释放，并引发细胞内活性氧（ROS）的产生，导致大量微生物死亡。由于自我保护策略，大量活细胞聚集在膜表面并形成具有分层结构的滤饼层，从而导致更严重的膜生物污染。
